I watched both videos and the third that came up and I don't see anything that would overly concern me if it was my cat. In the first video I would attribute his very slight movements to dreaming.
Even in the awake videos he looks sleepy but maybe he just woke up? And the meds he is on could be responsible for that too.
I think a video of him walking so we could see the slippage you mention might be more helpful.
But you are the owner and if this is a change for him then I do agree he needs to be examined. What's normal for one may not be the same for another and a change is what draws out attention.
I have no experience with epilepsy in cats or dogs, thank heavens. I hope you get this resolved. Sorry, guess I'm no help.