For years I've been working on an HL2MP mod called The Battle Grounds 2, and for just as long I've been plagued by this problem with my animation source files. This mod, before and after I joined the team, has a bad history of having contributors give us their compiled assets without giving us their source files. In this case, I already have a compiled .mdl file with working animations, but the source files when compiled yield different results.
As you saw in the video, while walking and reloading or walking and aiming the player's body bobs back and forth. I am not sure if this is a problem with the actual .smd animation files or if it's just a problem with the bones and weights in the QC's and QCI's. This problem has lasted so long that we've been forced to design our game around the animations instead of the other way around.
I've tried many times to decompile the working .mdl file we already have, but to no avail. I can get it to decompile, but whenever I recompile without even making any changes the player's body ends up squished into the ground whenever ANY of my game's unique animations play.
This is so important to me, that I'm considering paying whoever could definitively fix it for me!
For an in-depth look on the source files themselves, here they are:https://www.mediafire.com/?d2xpmp3on1ai8mk