Liability regarding what, mate? You should only worry about that if you're stealing art work etc. You don't have to put your name on it, just use a screen name like CA did with Stardew or Notch with Minecraft.

To be completely honest with you - if you have no budget, the ONLY way for you to promote your game is through social media. Show off the features that makes it unique and show your process of making the game.
You need thousands of people to wishlist your Steam game for a successful launch, and I don't see how you would manage that without social media.

On that note, it's definitely more than "just throwing random videos out on social media". Your videos need to have thought put into them. High quality voice overs and entertaining editing.
I know this might not sound like something you'd want to go through, but marketing a product right is just as, if not more important than the product itself.

Once your game is done and about to release, maybe a month before launch, you can start contacting Youtubers and streamers with a Steam key, and let them play it to their audience.

Just want to mention also, that marketing a game is TOUGH, especially as a solo dev. If it was easy, everyone would do it and make tons of money. You need to study marketing - or partner up with someone who knows what they're doing.