In some security guides listed that when you watching videos via Tor your real IP gets or might be disclosed. One of them says "You should turn off media.play-stand-alone and peerconnection.enabled to prevent leaks" or "also you should never use/watch html5 mp3 or another video formats because they use scripts/methods which can bypass Tor protection and disclose your IP directly" or something like that. Is this words worth attention or just regular useless tips? Does videos from casual sites are safe to view via Tor without privacy issues?
The Tor Browser developers have designed the Tor Browser to not leak your identity in its default configuration, and you should not need to change any settings. If there are features that can reveal your IP address with Tor's default settings, you should inform the developers. The option
media.peerconnection.enabled that you mentioned is already disabled in Tor Browser, and I don't see a privacy reason to disable
I also don't see any reason why you should avoid audio or video in the Tor Browser from a privacy perspective. If there is a reputable source that states this, please add it to your question. You should not play media that requires you to install additional add-ons or applications, such as Flash Player.