I lag out a lot which can cause players to go invisible. On rare occasions it also messes up the models like a scout showing up as a demoman jumping around. Nothing like running into a pub med to then be wm1'd because it was a pyro all along. I've heard of many others that experience the same thing
Since you lagged out not long before the clip that may have happened here.
However I never experience the model actually fixing itself which is pretty odd. For me it never fixes itself until I start recording a (new) demo