Came across this open source web video caption platform called NekoCap a while ago that let's you create and use community captions across many different video platforms via browser extensions. I've always felt that translation tech like this is important to help break down the international barriers that exist between online communities and to be able to get people in the West out of our cultural bubble more at scale.
Anyways, I finally got around to trying to make subs for it and it was the highlight of my day. Being able to put the typically otherwise unproductive repetitive labor involved in learning a language to use creating something that enables the content I enjoy to be shared to others who would otherwise not be able to enjoy it was incredibly fulfilling. Gonna try to do this a lot more regularly now.
10/10 would recommend.
Also in case there are any Genshin Impact fans here, the video I made NekoCap subs for is here: https://www.bilibili.com/video/BV1wy4y1b7jz
I'm a huge fan of translating (songs, videos, etc.) as a language learning exercise. It forces you to look at the languages and language in general in a way that is hard to achieve otherwise. It's also an important skill that is in my opinion separate from just knowing the languages well. Highly recommended.