Time to rebuild?

I watched the video. Can't say I've ever done this test on a gas engine, but it is very common on my M-B diesels. Those owners would be very happy to see such minimal blow-by. Most diesel engines show puffing from the oil fill cap just at idle, but they also have 400 psig compression (new, <300 psig when old and getting hard to start on cold mornings). If you had the PCV valve disconnected in the video, then it is probably "as expected". The PCV system sucks up all those vapors, and the blow-by flow probably wouldn't overwhelm it. To feel confident in the engine, turn it over by hand. You can use a socket on the crank bolt (many slants need to add a bolt, same size as Hemi's) if tugging/pushing on the fan belt doesn't work. If you feel 3 strong "air springs" per rev resisting you, and each takes >5 sec to hiss down and let you proceed, your engine has excellent compression, and you can sleep well.