I’ve had the physical copy for as long as I can remember, and I played it a lot as a kid. I might even have the demo, but is it worth to speedrun? It’s probably one of my favorite games, but I’ve never tried to speedrun anything, and I don’t know a way to record my 3ds.

Speedrun is a hobby, so it would be the players themselves, not others, who would determine its value.

For my part, I designed my own route and made a video of it in order to learn about speedruns in this game that no one else had run before.

But even if the game already has a runner, the best way to learn more about the speedrun is to actually imitate the play.

And by the time your intellectual curiosity is satisfied, you will have mastered the speedrun technique.

And once you get that far, you'll probably want to play speedrun, too.

Of course, this is if you find value in satisfying your intellectual curiosity. The value one finds in speedruns is different for everyone.

As for recording the 3DS, you can use a video camera to take pictures directly, or if you have the money and interest, you can try your hand at capturing game screens.

It's a very fun speedrun in my opinion, but I agree with syo_dai that you will have to decide for yourself if it's worth doing. It is very challenging.

To record directly from a 3ds you need to have it modified to include a capture card. In the US you can use this service if you have a "New" Nintendo 3ds specifically: https://3dscapture.com/order.html

You can also order an already-modded 3ds from someone like Delfino Customs: https://delfinocustoms.com/product-category/modifications/

There may be other options as well which I'm not familiar with. To syo_dai's point, even though it doesn't look as nice, it's totally fine to record your gameplay with a video camera if you can't invest the time and money for a modified 3ds.