With those videos, it's hard to tell if that is chain slap or what, but given how that chain is moving, I'd do an adjustment.
I caught some hell for this because it's dangerous, but I'll describe what I did. I put the bike up on the rear stand, cleaned and oiled the chain loosen up the axle nuts. Then I adjusted the chain to get it close. I then ran it on the stand in 1st gear at idle and adjusted the chain both for how tight and side to side. I did this by SOUND. I got it so close that 1/8 turn on either side would cause more noise. It takes a bit of time, but I was getting a few noises from mine and this got rid of them.
The chain has two adjustments, how tight and the alignment of the sprockets. They have tools to make sure the alignment is right, but you can do this by sound. In addition you can fine tune (IMO) how tight the chain is. I doubt the alignment took can get to 1/8th of a turn.
I clean and adjust the chain this way and I catch fire because of the danger, but I still do it.