I guess i could point out a few things you already knew you were doing...and some things about the match up in general...just my analysis...
Your samus is so fast and has such a good cross up game on shield and a really good boxing game, something samus doesn't get credit for since its difficult to do. However, snake's shield and his f-tilt and grenades and stuff snake does just out prioritized a lot of the things you went for. I agree that you were out playing him, like, it took him awhile to adapt, but yeah, he caught on to some gimmicks. But more importantly than that was that you didn't change up your missile game. I wanted to see more double missile, something other than sh missile. It became rhythmic, and he got used to just walking and shielding. I think I saw you do one missile to grab in the entire video. Its probably not my place to say anything really, since your samus is better than mine, but if I can help then i hope I do. When I use samus, I like to get into people's head. People hold shield down when they see a normal missile, and they over react to mbb. He was hiding in his shield a lot and didn't really spot dodge. I would have went for some grabs if I was at low %. Also, zair to nB could have worked. He was getting used to you landing with zair and popping back up to catch him with another one, so he would airdodge and just run towards you and shield or something. nB would have kept him from running straight into you.
that's all i got for now u.u I really love your samus...I dont get to see too many samuses anymore and its really nice to see you using her like this