I´m not sure it's good to upload high quality videos. The game is rather short (40 min probably), and sometimes I feel the devlog might be too revealing. I will release a trailer though, but I think I prefer the devlog to be more of a tease.
I agree that there are some situations where you wouldn't want to reveal too much but there are a few things to consider as there may be a few different types of audiances.
For me a devlog is something where you show your game to (mainly) other developers and can include everything. In fact, usually, the more details you include, the better. This can give a good idea to other developers how you create your game. From level to character designs, etc. So, for videos, I was mainly thinking of showing your models, environment, etc during development and not just the final gameplay.
For people who are mainly interested in playing your game it's better to do something along the lines of what movies do: show a main trailer (or a few) and some posters/screenshot that is usually enough to give people an idea if they want to play your game. For those that are really interested in updates, a few few behind the scenes or work in progress images can be shown to keep people excited.
So, it can be beneficial to tailor your communication to your specific audience.
It's my final project in school. I don't see it as a school project though. I´ve been wanting to do a more ambitious game project exploring interactive narratives for many years (I´ve been making smaller (secret) games for lots of years), so for me it's a more of a personal project and even though I´m going to sell it on Steam hopefully, my main goal is to simply create something to be proud of. I will market it, but not in a formal way.
Oooo! Secret games!
Since you mentioned your game is short, you'll probably have price it "right" as it seems like not all but many people seem to equate value with length of game. The main reason I mention is that last year Steam introduced a new refund policy and sounds like one criteria is that player has played the game for less than two hours. If the game has a reasonable price then that shouldn't be an issue but wanted to mention that. If I remember correctly, I've read on the the Steam website, that they'll help you set the price so that shouldn't be an issue.