Video ads platforms for publishers ?

Hi hats,

I'm currently running CPL campaigns on one of my websites and I'm wondering to move to video ads.

My visitors could take around 30 seconds to watch the video before I unlock (for example, if I do lock) a kind of result.

Which platforms would you suggest me for that ? (google ads refused me because of not enough contents, but I do have some, and I have engaged visitors, anyway...)

I've heard of "spotxchange", did some of you use it ?

And how much do we win for video ads per view when we display a video for around 30 seconds for example ?

Thanks,