Hi BL:
In my experience, what you are seeing is an insect. I don't know this to be sure, but what was the temperature that night? If it was warm enough, perhaps it was an insect. If you ever get the chance, take your night vision camera and point it where you know insects to be, and you will find it will be very similar. I am not saying this isn't something valid, it's just something to think about.
Does your basement have a dirt floor? Is it relatively clean as far as dust? Did you have the heat or a/c on that night? I don't know.. we have the A/C on right now in Texas since it's been warm. Are your windows secure so that not many bugs get in? You might try to use an external IR light to capture even additional footage. You can get one off Ebay relatively cheaply. In this video clip, I don't think it was dust, as it did not move as a dust mote would, but then I don't know if you had any vents on or anything.
Good luck and I'll be looking forward to your follow-up on this. Really neat!
CG