I think the first speedrunning-related I ever saw was Morimoto's SMB3 TAS somewhere between 2003 and 2005, it wasn't labeled as a TAS back then (TAS haven't been invented yet Kappa), that run was awesome ! But I didn't care much about it, what's the point of playing on the same game for 15 years when you can play new games like GTA3/VC/SA, MGS2/3, FFX, TimeSplitters 2, Dark Cloud, Kingdom Hearts. (PS2 so good Kreygasm )
Later (2005 or early 2006) I discovered SDA, I remember downloading a run (1GB was a lot back then), it was a segmented run of MGS3, but it wasn't fun, the guy skipped all cutscenes and codec calls, and was rushing through levels with running or rolling everywhere. I was expecting superplay, but the intended way all stealthy and shit
Then, years later in May 2012, I accidentally ended up watching SGDQ2012 with french commentary (it wasn't a restream at the time, just audio commentary), it was awesome, the skills, the skips, the glitches Kreygasm. in November 2012, I watched NumberSMW marathon on twitch, it was the day I discovered people were speedrunning games EVERY FUCKING DAYS !!! on twitch, so I started watching it more and more.
Personally I don't really speedrun any games (I'm not a very skilled nor patient gamer) but I like to learn route/tricks/glitches, I'm trying to understand why runners do thing the way they do, etc...