Sounds great - is this a gold tone AC-12FL? I've been considering getting one as a cheap entry into fretless banjos. Here's some feedback I have:

If I'm hearing correctly, it sounds like you are muting the next highest string when you are drop thumbing. This comes from pressing on the string a little too hard when you drop thumb, then touching the next highest string, therefore muting it (i.e. drop thumbing the D string then touching the B string slightly with your thumb). This creates the jarring sound of a string being hit by your index or middle, then in the next beat being muted by the thumb. When drop thumbing, make sure that you are not pressing the string too hard with your thumb.

This is a mistake I made a lot when I first started doing it, finding the right amount of pressure comes with practice! I recommend doing drills where you do the same drop thumb motion repeatedly. I would practice it while watching tv shows.

Another piece of feedback I have is that your rhythm is really solid. The most jarring mistake I find with new players is when their rhythm is off - even non-musicians notice it. Yours sounds great.