Here is how one idea how to do the categories:
GT & prototypes
- modern after '95 gt and racing prototypes racing, practise and lone laps
- includes cars like these (not limited to): fia gt, superGT, lemans cars, alms, dtm, GT1, GT2, GT3, GT4
- I did put modern after '97 dtm in this category becuase to me they are more like gt cars than touring cars. And supergt is there too.
Single Seaters
- self explanatory imho. Formula cars.
- cars like caterhams, ariel atoms and whalen modifieds do not belong in this category though
Rally
- includes rally, safari, rallycross and rally sprints and sometimes hillclimbs
- also sand buggies, baja trucks
- tarmac, snow and gravel
- all eras
- no dirt oval racing nor monster trucks
Touring
- btcc, wtcc, super2000, stcc, dtm pre '97, v8 supercars
Stock cars
- sprint cup, nationwide, trucks, late models, whalens, modifieds
- also include, short ovals
- both oval and road races
Motorbikes
- motogp, wsbk, motocross, enduro
- no bike drag racing
Drift
- self explanatory
Vintage
- classic footage of vintage cars. 80s and pre 80s cars
- imsa racing, trans-am, intereserie, sportscars
- also the vintage cars racing today
Club racing
- all other racing cars that do not belong in other groups like locosts, beetles, normal cars, supercars, tuned cars
- also trackday vids
School & educational
- instructional videos about driving techniques
- videos showing the driver inputs in detail
Others
- dragracing, dirt ovals, rc onboards, boat racing, tractor racing, truck racing
Some cars are pretty hard to put in certain category without it being a bit confusing to the user. Like dtm and v8 supercars. But imho it is more important that the videos are categorized well instead of the uploading being easy. Oval is not imho a good category because where do you put nascar onboards from road courses then?
Also it would be nice if there was a tag cloud where you could pick more precise identifying tags to provide some additional info and also to make it easier to find more similar vids. Tags like porsche, ferrari, le mans, nordschleife, time trials, crash, close racing, spin, great sound, hd, snow, gravel and so forth. But instead of just writing them like in youtube you could add them yourself and just offer the user to tick them on during upload with checkboxes.
You could also write some kind of short description as what are the requirements for a vid to be approved on your site. I sent about 30 vids and I only see couple of those being approved