Is there anything you installed in the last little while that might be running in the background taking up some memory?

You can do a Ctrl-Alt-Del and see what kind of processes are running and how much CPU they are taking up.

I don't know enough about RAM, but maybe one of them is going bad.

Someone might have a better idea.

Bob, you are talking about videos stored on your computer right?

If not, maybe your connection to the internet is a little sluggish.