I haven't participated in that contest but i do hope that does who do the choosing of winners will do thorough screening before announcing the winners to weed out the cheats.
Based on my experience
[in regards to similar competitions being run by the respective team members, from outside] + their current rules, I have a strong feeling that won't be the case
[I hope I'm wrong]...
- Even if they want to completely get rid of those kinds of entries, it's way too hard to spot and find the original sources [video entries] in comparison to competitions requiring participants to submit an image.