OK, the sound at the 1:24 mark appears to be just not in gear, and everything that you do there suggests that it was not all the way in gear.
I did not hear anything at the 2:40 mark but it looked like it didn't want to go in gear.
I find the 4:55 mark POSSIBLY a bit more troubling as it seems like the noise continued well after you depressed the clutch, and with the proper throw, even if it was just not getting into that gear, it should have stopped. BUT reverse is not synchronized so if there were any kind of RPMs over idle then that noise wouldn't be surprising, and I just couldn't tell exactly what RPMs you were turning... so it may just be a matter of it not being all the way into gear again.
I am thinking linkage adjustment is part of the issue. I'd also look at the nosecone mount and make sure it is tight and that the rubber hasn't pulled away from the metal. Usually when you don;t have enough shift rod throw for the 3 down gears (R, 2, 4) then you have buckets for the 2 up gears (1, 3)
One thing you may consider is to pull the shift rod off the nosecone of the transaxle and put the car in gear with vice grips, right at the hockey stick and see what it does. OR you can put it in reverse, gently disconnect the shift lever, and then see if you can get it "more" into gear at the nosecone.