I was expecting to watch somekinda movie based on beavis and butthead based on the title.
The movie turned out to be a reinterpretation of an audio clip from back to the future.
You took the spoken as a literal interpretation in your animation and the text at the end explained the joke.
The text itself saved an otherwise stupid movie with it's self parody.
The movie itself was surprisingly self aware of how stupid it is.
I don't always recommend using self parody since it can often be funnier to become a target for satire instead.
Here, self parody can be the only effective way to enhance the delivery of this quick gag.
I like the frame by frame and the facial expressions of biff.
It kinda reminds me of egoraptor's drawing style.
We all start with learning from different kind of drawing styles.
There is nothing wrong with borrowing from multiple drawing styles and combining them with others.
Keep practicing and your own style will evolve into something more distinctly yours.
I enjoyed this silly little skit.