problem with YouTube

hi. I have a Macbook Pro with Yosemite and just recently when I watch short youtube videos it will stop after a few minutes and the video screen will go black and the red bar disappears and so I have to reload the page. I have Kaspersky and it can't detect any intruder. Today I used disk utility to verify ad repair the hard disc but the problem persists. It seems like long videos are less likely for this to happen to.
Any ideas?

It might help us answer your question better if we knew your Mac's specs. I see that you are running Yosemite but a wide variety of Macs are capable of running that OS. If you need to check your Mac's specs go to the Apple menu in the upper left corner of the screen and choose "AboutThis Mac. . ."

I haven't used Kaspersky personally but is there any way to turn it off for a bit to test? I wonder if it is using enough processor cycles to cause the problems.

Mid 2010 MacBook Pro, OSX 10.10.5, 2.4GHz Intel Core i5, 8GB 1067 MHz DDR3, Intel HD Graphics 288MB

Get rid of Kaspersky and any other AV software that you might have running. Unless for some reason you're required to run it (school, job, etc) you really do not need an active AV application. Chances are it's eating into resources (as mentioned above by our moderator) and possibly causing the YouTube hangs.

I've had Kaspersky for over a year and this problem just started a couple weeks ago. And it don't happen when I watch Youtube movies, just short videos.
very baffling