Follow the link they supplied and look at the numbers involved.
If you upload 675 clips within 20 days that are accepted, they will pay you $280.
That is about 30 CENTS per clip -- less than Shutterstock pays for photos, and about 1% of what I normally get for video clips.
And even then, that is only if those 675 clips are all accepted, and only if done so within 20 days.
Sounds like a sucker bet to me...