Same problem here. It is completely random which videos it does this on. Based off the fact it is complaining about HTML5 video, I am betting this is related to some conflict between adobe flash player, and html5.
And please don't put this fix behind premium version of Deepbot.
I can say that if this issue isn't resolved in the next few days, I am leaving it for good. It is sad because I joined deepbot way back when it started.