This is a fan-made trailer with footage taken from different the Incredible Hulk and Captain America 1970’s tv shows, plus other footage.

Gene Simmons from Kiss doubles as the Destroyer, Iron Man is taken from the show ‘Exo-Man’, Black Widow is from ‘Electra Woman and Dyna Girl’ clips, whereas Hawkeye is from M*A*S*H.
There’s even Loki! It’s really a pity this version of the Avengers never got to be made, but at least we have more than fantastic Avengers movies now.

https://www.youtube.com/watch?v=oQ0PwWgLB-k