Lol! I tried to re-create that scenario you described the same evening I read it. I opened like 8 videos and had all of them visible in their own space running, my kid asked me if I was going crazy lol! Left them running for the duration of their episodes (30mins) she didn't mind at all, told her to come get me if anything looked like it was frozen or entire screen turns blue. Nothing happened and went on to Watch Dogs 2 and no issues. Maybe try resetting system overclock or if you don't use Virtual machines then disable everything Hyper-V related in bios and windows.