That is so sad - i find it strange - but understandable, sort of - that someone thought to film it. Poor puss, there's a desperation in his behaviour, and yes, they know. I hope someone helped him afterwards, I bet he followed when his mate was lifted from the road....
Like pericat, I had twin boy cats, one died aged 10 at the vets and the other one KNEW that morning before we did - and the one left behind did come out of himself. Wierdly, cat 2 died the same weekend the following year.