No sound in some facebook videos

Eric, thank you for your reply!

Safe mode totally disables my system audio (no audio output in system preferences).

Creating another admin user account doesn't solve the problem. Same results as with my original admin account.

Here is what Etrecheck spit out:

EtreCheck version: 4.2.1 (4C020)

Report generated: 2018-07-06 13:57:18

Download EtreCheck from https://etrecheck.com

Runtime: 3:17

Performance: Good

Problem: Other problem

Major Issues:

Anything that appears on this list needs immediate attention.

Gatekeeper disabled- Gatekeeper security protection is disabled. This computer is at risk of malware infection.

Minor Issues:

These issues do not need immediate attention but they may indicate future problems.

High battery cycle count- Your battery may be losing capacity.

Small backup drive- Time Machine backup drive is too small.

Unsigned files- There is unsigned software installed. They appear to be legitimate but should be reviewed.

System modifications- There are a large number of system modifications running in the background.

Corrupt hosts file- Hosts file is corrupt.

32-bit Apps- This machine has 32-bits apps that may have problems in the future.

Hardware Information:

MacBook Pro (Retina, 15-inch, Mid 2015)

MacBook Pro Model: MacBookPro11,5

1 2,5 GHz Intel Core i7 (i7-4870HQ) CPU: 4-core

16 GB RAMNot upgradeable

BANK 0/DIMM0 - 8 GB DDR3 1600 ok

BANK 1/DIMM0 - 8 GB DDR3 1600 ok

Battery: Health = Normal - Cycle count = 747

Video Information:

AMD Radeon R9 M370X - VRAM: 2048 MB

Intel Iris Pro - VRAM: 1536 MB

Color LCD

Drives:

disk0 - APPLE SSD SM0512G 500.28 GB (Solid State - TRIM: Yes)

Internal PCI 8.0 GT/s x4 Serial ATA

disk0s1 - EFI (MS-DOS FAT32) [EFI] 210 MB

disk0s2 () 500.07 GB

disk1s1 - Macintosh HD (APFS) 500.07 GB (430.12 GB used)

disk1s2 - Preboot (APFS) [APFS Preboot] 500.07 GB (23 MB used)

disk1s3 - Recovery (APFS) [Recovery] 500.07 GB (518 MB used)

disk1s4 - VM (APFS) [APFS VM] 500.07 GB (1.07 GB used)

Mounted Volumes:

disk1s1 - Macintosh HD 500.07 GB (68.17 GB free)

APFS

Mount point: /

Encrypted

disk1s4 - VM [APFS VM] 500.07 GB (68.17 GB free)

APFS

Mount point: /private/var/vm

disk2s2 - Р**************************e 499.76 GB (4.38 GB free)

Case-Sensitive Journaled HFS+

Mount point: /Volumes/Р**************************e

Network:

Interface fw0: Thunderbolt FireWire

Interface en4: iPhone

Interface en0: Wi-Fi

802.11 a/b/g/n/ac

One IPv4 address

Interface en3: Bluetooth PAN

Interface bridge0: Thunderbolt Bridge

iCloud Quota: 126.72 GB available

System Software:

macOS High Sierra 10.13.5 (17F77)

Time since boot: Less than an hour

System Load: 3.11 (1 min ago) 7.96 (5 min ago) 4.68 (15 min ago)

Configuration Files:

/etc/hosts - Count: 11 - Corrupt!

Security:

Unsigned Files:

Launchd: /Library/LaunchDaemons/com.oracle.java.Helper-Tool.plist

Executable: /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Resources/Helper-Tool

Details: Exact match found in the whitelist - probably OK

Launchd: /Library/LaunchAgents/com.brother.LOGINserver.plist

Executable: /Library/Printers/Brother/Utilities/Server/LOGINserver.app/Contents/MacOS/LOGIN server

Details: Exact match found in the whitelist - probably OK

Launchd: /Library/LaunchAgents/com.oracle.java.Java-Updater.plist

Executable: /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Resources/Java Updater.app/Contents/MacOS/Java Updater -bgcheck

Details: Exact match found in the whitelist - probably OK

32-bit Applications:

23 32-bit apps

Kernel Extensions:

/Applications/Adguard.app

[Loaded] com.adguard.nfext.kext (1.0.17 - SDK 10.13)

/Applications/DiskWarrior.app

[Not Loaded] DiskWarriorPreview.kext (Alsoft, Inc, 5.0 - SDK 10.5)

/Applications/Parallels Desktop.app

[Not Loaded] prl_hypervisor.kext (Parallels International GmbH, 13.3.1 43365 - SDK 10.9)

[Not Loaded] prl_netbridge.kext (Parallels International GmbH, 13.3.1 43365 - SDK 10.9)

[Not Loaded] prl_usb_connect.kext (Parallels International GmbH, 13.3.1 43365 - SDK 10.9)

[Not Loaded] prl_vnic.kext (Parallels International GmbH, 13.3.1 43365 - SDK 10.9)

/Applications/TechTool Pro 10.app

[Not Loaded] spdKernel.kext (Micromat, Inc., 1.0 - SDK 10.11)

[Not Loaded] spdKernel_10.8.kext (Micromat, Inc., 1.0 - SDK 10.8)

/Library/Extensions

[Loaded] MB_MBAM_Protection.kext (Malwarebytes Corporation, 3.3 - SDK 10.13)

[Loaded] ufsd_NTFS.kext (Paragon Software GmbH, 15.2.319 - SDK 10.10)

System Launch Agents:

System Launch Daemons:

Launch Agents:

Launch Daemons:

User Launch Agents:

User Login Items:

CheatSheet Программа (Stefan Fuerst

(/Applications/CheatSheet.app)

AdGuard Программа (?

(/Applications/Adguard.app)

CleanMyMac X Menu Программа (MacPaw Inc. - installed 2018-06-24)

(/Applications/CleanMyMac X.app/Contents/MacOS/CleanMyMac X Menu.app)

Alfred 3 Программа (?

(/Applications/Alfred 3.app)

BlueHarvest Программа (Ross Tulloch

(/Applications/BlueHarvest.app)

AutoMountLaunchAtLoginApp SMLoginItem (Mac App Store - installed 2018-05-12)

(/Applications/AutoMounter.app/Contents/Library/LoginItems/AutoMountLaunchAtLogi nApp.app)

1Password Launcher SMLoginItem (AgileBits Inc. - installed 2018-07-02)

(/Applications/1Password 7.app/Contents/Library/LoginItems/1Password Launcher.app)

BartenderStartAtLoginHelper SMLoginItem (Surtees Studios Limited - installed 2018-06-24)

(/Applications/Bartender 3.app/Contents/Library/LoginItems/BartenderStartAtLoginHelper.app)

1Password Extension Helper SMLoginItem (AgileBits Inc. - installed 2018-07-02)

(/Applications/1Password 7.app/Contents/Library/LoginItems/1Password Extension Helper.app)

Irvue Launch Helper SMLoginItem (Mac App Store - installed 2018-06-24)

(/Applications/Irvue.app/Contents/Library/LoginItems/Irvue Launch Helper.app)

Internet Plug-ins:

AdobeAAMDetect: 3.0.0.0 (installed 2018-04-29)

FlashPlayer-10.6: 30.0.0.113 (installed 2018-06-24)

QuickTime Plugin: 7.7.3 (installed 2018-06-24)

AdobePDFViewerNPAPI: 17.012.20098 (installed 2018-06-01)

AdobePDFViewer: 18.011.20040 (installed 2018-06-01)

Flash Player: 30.0.0.113 (installed 2018-06-24)

Bco: BCO System Cryptographic Plugin 1.0.0.14 (installed 2018-07-04)

JavaAppletPlugin: Java 8 Update 171 build 11 (installed 2018-04-27)

Safari Extensions:

3rd Party Preference Panes:

Backblaze Backup (installed 2018-06-29)

Flash Player (installed 2018-06-02)

Java (installed 2018-04-27)

NTFS (installed 2018-04-20)

TechTool Protection (installed 2018-06-24)

Time Machine:

Skip System Files: No

Mobile backups:

Auto backup: Yes

Volumes being backed up:

Macintosh HD: Disk size: 500.07 GB - Disk used: 431.89 GB

Destinations:

B****p [Network] (Last used)

Total size: 499.76 GB

Total number of backups: 44

Oldest backup: 2018-06-09 16:35:01

Last backup: 2018-07-06 12:49:30

Top Processes by CPU:

Top Processes by Memory:

Top Processes by Network Use:

Top Processes by Energy Use:

Virtual Memory Information:

Diagnostics Information (past 7 days):

2018-07-06 01:40:14 com.apple.WebKit.Plugin.64 CPU (once)

2018-07-04 21:52:13 Transmission.app Hang (once)

2018-07-03 18:20:16 Adobe Photoshop CC 2018.app CPU (3 times)

2018-06-30 01:55:06 Skype.app Crash (once)

End of report

Eric,

I tried all of the above, but nothing helped. Quit Adguard, disabled all Safari extensions and uninstalled Cleanmymac. I even tried rebooting after. No luck...

And I don't have Cocktail installed.

I still think that problem is related to Safari somehow. Or Adobe Flash. Will try to reinstall it and see anything changes.