This isn’t my video, but the tempo slows down to normal between levels, and speeds up in game, and the gameplay feels faster than I remember it (tho I haven’t played the C64 version since I was a kid, so a little hard to tell). What I’m experiencing seems exactly like what’s in the video.
I’m playing in NTSC mode on the C64U. I haven’t been able to find any info confirming this game is supposed to be played in PAL or NTSC mode.
Edit: It does seem like normal if I do PAL. Would be nice to get a confirmation on the page that’s the intended mode, if that’s actually the case.