If you cannot find the video you're looking for check actual product listing itself, there are videos associated on most of the products.
https://youtu.be/LQm7FwDa5J4 RCGF60RE rear exhaust
https://youtu.be/id3RMadQSAU RCGF70cc twin 24x8 prop
Product review RCU on the RCGF70cc twin: https://www.rcuniverse.com/articles/review/engine-review/rcgf-70cc-twin-cylinder-gasoline-engine/ "will need to copy and paste to view"
https://youtu.be/W4M5bakiLGw RCGF35cc Rear exhaust
https://www.youtube.com/watch?v=HkPqb7jT4HM&feature=player_detailpage&x-yt-ts=1421914688&x-yt-cl=84503534 RCGF 30cc TWIN cylinder 3.7 h.p. smoother than a babies rear 7000 rpm 19x8 prop
https://www.youtube.com/watch?v=55ac8d-1frg&feature=player_detailpage RCGF 120cc Gas r/c engine 12.5h.p. awesome power house
https://www.youtube.com/watch?feature=player_detailpage&v=DzJlLb96Gos RCGF 60cc single cylinder 6.0h.p
https://www.youtube.com/watch?v=zt3ckBQv3HM&feature=player_detailpage Authentic Scale 200cc 9 cylinder radial engine
https://www.youtube.com/watch?feature=player_detailpage&v=O8B12ebxAmM#t=2 RCGF 10cc Gasoline r/c engine 1st test
https://www.youtube.com/watch?feature=player_embedded&v=HUuMtVHmQtM DJI Phantom quad copter
https://www.youtube.com/watch?feature=player_embedded&v=ahu-kxUT_Uc 5.8 Ghz Video transmission set (FPV)