So the Brinno cam makes AVI files? Here is a cheat... (I think)
Import the brinno time lapse avi into SA. It will think they are just regular videos like from a Trophy cam or something.
Now outside SA, rename them from AVI to TLV. ie change the extension from AVI to TLV. Go to a different media set, then back to that one in SA. Now go to the Motion tab, you should be able to process them.
I will have to put some changes in to "force" recognition for time lapse videos that end with AVI, maybe during the import media.
Let me know if this works.