Taking a look at their page, and doing a little digging, it appears to be stolen content. In addition to the style of the sales page, style of testimonials, domain name, fact their servers appear to be in panama, use of name servers, etc which all would indicate a bit of a shady site.

Appears that they've ripped off content from pixbay (where authors provide content for free), and are reselling it, but might even have been taking from sites like motionarray & envato elements, where they recently devalued authors work as well (so in essence, it's like $0.50/$1/video, etc from those sites too).

Even though some of the content appears to be from pixbay (https://pixabay.com/en/videos/list/), and they allow 'free' commercial use, the license does not allow for simply repackaging/reselling as stock photo. So you might contact them, see if they can do something about the stolen content. However, they only have about 7,000 free videos. So... that's another 14,000 unaccounted for, probably taken from the other sites mentioned above.

This site was started 2018. Various 'samples' appear to be have been produced/used way before that.
I.e., looking at the sample images in their sample "searchable database"
http://stocknation1.imgix.net/secret/images/timelapse.png

#1) I.e., here's a youtube image (originally posted 2016)
https://www.youtube.com/watch?v=NEkgCT_Y8OA

same cloud timelapse

#2) Then another item appears in a template in motionelements (a video within a template) (the 2nd timelapse below that)
https://www.motionelements.com/ja/after-effects-template-9347535-holographic-display-02

(same timelapse)

It might be worth a few people signing up just to see if their content is there. There's a few things that can be done if they are selling your stolen content.