Did you get all the fittings tight when you put the lines back on? I would guess an air leak or newly-formed crack at the prefilter since you disconnect there to do the purge.
I once had a fuel leak there near the clamp and didn't notice any fuel leaking there, but it sure let air in, stopping the engine. Or as Diesel911 said, the main filter is clogged. You could let some fuel out at the nut near the bottom of the filter can to check what comes out (see if it's watery or dirty).

Couldn't hear much on the video except what sounds like a very bad exhaust leak (or do you even have the entire exhaust system on?)

__________________
1976 240D "Katja"