can someone explained the self employed feature?

For the video editing table I believe your sims makes royalties off of videos like youtubers make money off of videos. Your sim can also get brand deals that'll ask you to upload certain types of videos. I think in one IronSeagull's video a brand deal wanted his sim to use the drone to film a fishing spot and i think there was a bonus if the sim was filmed fishing as well.

As for the music table idk as I haven't seen any videos on it.