They are a lot smaller than marker ticks, and they only occur at the end of an event. It looks to be random because I can't find a correlation to the source files.
This project was a collection of one to two minutes of several high-school stage plays that the client wanted on a single DVD. Some of the source files were .mov files, some .dv files, a few .vob files and the rest were .avi.
It's the first time I saw these red dots (trust me, they are red), but there doesn't appear to be a relationship to the filetype.
I agree with Kelly. They're embedded markers. Now, they look orange to me as well in the image which would indicate Markers. I've duplicated the "look" with a clip that has embedded regions. Mine were green (i.e. the region marker color). The only "Red" markers I know are CD markers.