I watched "Livin' on a Prayer" in 4K and and looked great, even when watching on my phone! Before the 2nd chorus as it changed to colour, that's when the image really popped.

"It's My Life" looked decent but unlike "LoaP", it did look upscaled and was cropped to 16:9. There are some 4:3 section during the original video and the aspect ratio changes here and there, but considering most of the shots are in widescreen it's no big deal.

Can't wait to see more videos reuploaded in 4K, but unfortunately prettymuch anything from "It's My Life" onwards will be upscales and I presume they were originally shot digitally and therefore locked at 480p/1080p.