Hey, Tarandeep. We're really sorry that we weren't able to get to your run before the VOD expired. Verifying runs is a volunteer job (that is, nobody is getting paid for this) so sometimes things can take longer to verify.
However, we do note this in the game rules under Video Submission Guidelines: "Recommended: provide a permanent video link rather than one that may expire (e.g. Twitch VODs). We suggest using the Twitch highlight feature or uploading to YouTube if possible."
Again, we are very sorry for the inconvenience. Consider using the highlight feature in the future as this will also let future players watch back your run and makes it easier for us to verify by only including the run in question.
You can definitely speed run on Switch! As long as you have someway to capture your gameplay, you can play on any platform! If you play on Switch, you will be playing with the "Vanilla" Category, whereas playing on PC allows you to also do "Glitchless" runs if you desire. But all ways are valid to play! Welcome to the game!