Basically what I meant to say is that it's a flash problem, and flash was not just interrupting my youtube videos but was also taking up a lot of my RAM cuz I always have dozens of tabs open at once ... nothing solved both problems until I downloaded click to play after someone from the macrumors forums suggested it! I hope is helps
Ah yes, it was indeed a Flash problem for me. After doing many of the previously suggested fixes, nothing worked. But the fix was quick and easy. I went to the Adobe Flash test page:
It showed my flash player was't working, pointed me to the download and install, and voila, YouTube works beautifully in Safari now!
If you have youtube account and you're logged in, check first that you allow advertisement in youtube's parameters.
I had videos blocked every minute and half or two minutes for months now... Since I ticked the box "Allow advertisements to be displayed beside my videos", all videos play with no stop !
Why? No idea but it worked for me... Hoping it helps.
I have just started to get this problem in the last day. I've realised that the problem only occurs when I have my external Tascam Us-122l USB Audio I/F plugged-in. This all worked fine 2 days ago.
Now if I plug-in the audio I/F (via USB) it stops the vieo playing after 10-20 secs and I have no sound at all. If I unplug the USB it all works fine.
I'm not sure if this is a Safari or Flash issue? I can happily play iTunes and watch Youtube videos within Firefox using the audio/IF but not Safari!
BTW, I've deleted and reinstalled flash