I could make unlisted videos and provide you the link if that works better for you
Oh, also I downloaded the temporary fix version and is still giving the same error in console when trying to open Crystal Mountains level, not sure what's going on with it
EDIT: I've tried launching multiple levels and every time it closes the the game without any warning. It also resets settings like forcing the mod to launch in windowed mode every time despite my changing it to borderless
2nd EDIT: I figured out why the Crystal Mountains level still doesn't work. I went to Serious Sam Classic The Second Encounter\Mods\TheSequel\SoundsF\Destruction and found the sound file it says is missing. You have it named Impact_Stone01.wav when it should be named Impact_StoneLarge01.wav. I renamed it though I can't tell if it worked or not because instead of booting me back to the difficulty screen it again showed me a black screen for a second after the loading bar finished and closed the application
3rd (and hopefully final) EDIT: Luckily I still had the old .gro file of the mod I had downloaded a couple weeks ago and it seems to be working fine. I tested and renaming the file did indeed solve the issue with not being able to load Crystal Mountains level