I updated to OS X Yosemite and my iPhotos were put into Photos but I can't get my videos to play on my macbook pro or my iPhone now

Why not? (remember we can not see you so you have to give us details)

and iPhoto still works fine (you do need the current version 9.6.1 - if you do not keep your system up to date see Can't Update iPhoto because it is not available in the App Store

)

LN

again we can not see you so rather than

I get a quicktime can't open them message at photos

we need the compete, and exact error message - that gives us information to help you

LN

There have been other reports of Photos not being about to play some formats. You can try the fix that léonie found and posted here:

léonie i

Nov 26, 2014 7:34 AM

Re: (OSStatus error -54)

in response to Chris Pugh

Solved

One reason why videos don't play after extensive cleaning might be a missing cached file.

With MacOSX Mavericks and Mt. Lion it helped to rebuild the cache using a Terminal command:

Try this fix posted by andyBall_UK

• Open a Terminal window (the Terminal.app is in Applications > Utilities)
• Copy and paste the line below into the Terminal window, hit return and enter your administrator password.

sudo /usr/libexec/xpchelper --rebuild-cache

If you do not want to use a Terminal command you can achieve the same thing by booting into recovery and reinstalling the system on top of your current system - don't wipe the drive again. OS X: About OS X Recovery

A workaround for me on a couple was to click and drag the video thumbnail to the Desktop. That will start a conversion to a format that Photos could use. When the conversion is completed import the new file into Photos and try playing it again.