hi,
the segmentation method (how you extract what is your interest from the rest of the image) is very critical in video tracking
background subtraction is a basic way to extract blob and it works only in certain conditions of light (if you want to track something outdoor, you should use an adaptive background subtraction method)
moreover, there is no general method to do video tracking, it depends on what you want to track and how it is filmed
so, the first thing is to have a good image, with not too much lighting changes, good contrast between background and features to track
then you can start thinking about segmentation, and the segmentation accuracy depends on the quality of the video
you may need to do something more than just background subtraction, for example, you could apply some morphological filter to remove noise
after that, you can start tracking
you could also apply a threshold on the blob size to not track very small blob
blob of interest are often surrounded by very small blobs due to segmentation noise
but you can have a look at pix_opencv objects,
there is [pix_opencv_blobtrack] which implements a whole processing chain, including foreground extractor, blob detector, blob tracker and follower
I'm not sure it's included in pd-extended, but you can find some binaries on build server
hope this help
antoine