@Sparks0829 This is definitely not an issue with specific content. Moreover, it's not specific to HDMI; it also happens through a Thunderbolt-DP cable. All content is like this, be it something played via YouTube, a local content played using QuickTime player, and even screencasts that I made. One difference is that YT content (probably because it's streaming) quickly forwards, stutters and then hangs in the middle, while local content just whizzes by to the end. It's almost as some piece of multimedia subsystem continuously failed to play one media chunk after another, but I'm just speculating.
I started experiencing it a couple of days or weeks ago (it was not there before, and I didn't make any changes to my hardware except from connecting and disconnecting headphones). Here's my setup: 16-inch MBP (M1 Pro), Sonoma 14.4.1. Video goes through a Thunderbolt-DP cable to a Gigabyte G4WCQ A monitor, and then, using a regular audio cable, to external speakers. There's usually an OWC 11-port Thunderbolt dock in between, but I've also tried without it, to the same result. I also tried without the external speakers, just using the monitor's built-in ones. Surprisingly, even restarting the coreaudio daemon doesn't help, so the issue must be somewhere deeper. The only thing that helps is a full reboot or disconnecting the monitor and switching to the built-in audio device.
Also worth noting is that it's not really important that the monitor is hooked up to the laptop; the audio must go through the monitor itself. After switching to external headphones connected either to the built-in port or the Thunderbolt dock's audio interface, the issue disappears — until the headphones are disconnected.