On Mastodon, since there is no algorithm, hashtags are necessary for maximum exposure.
If you post about your new video then it will get pushed out to all of your 454 followers and the live feed.
But, if you also put some hashtags in your post it will get pushed out to 100s or even 1000s of other people that may not follow you but they do follow those hashtags.
A lot of people follow #Gaming #VideoGames #Games #RetroGaming
In turn that could lead to more views and subscribers!