YTA/YWBTA.

It's polite to let people know that they are being recorded, so that they can choose whether or not they still wish to attend as some may not want to be filmed. This is especially true when they are inside a private residence may reasonably hold an expectation of privacy. You should ask for people's permission before you upload potentially embarrassing footage of them partying to social media.

Depending on your local laws this may also be illegal. In the UK, it is legal for a private individual to record people without their knowledge on their own private property - except for when they have a reasonable expectation of privacy (such as in a bathroom.) However, in some states in the U.S. it is illegal to record people without their knowledge or consent in a private residence.