It looks like you're using cheats in the first video. Double-tapping up at the top of your jump NEVER gives you extra height, and certainly not enough to get you high enough for that. I don't see any possible use for either of these tricks. Even in 100%, it's faster to just space jump high enough over the pillar and spark (of course saving that spark for the other tank in that room).
I can do this without using space jump or high jump boots. Just use shinespark. When you get on top of the tower during shinespark, jump and use super jump left mid-air (A followed by B). There should be a slope right above the door on the left. After that, jump and super jump right (again, do that in mid-air). If you did this right, you can really get early super missile.