Thanks for the video! 
This is a compacted road. Some loose gravel on top of it, but probably bikeble without the bike trailer? 

See example photos here
https://wiki.openstreetmap.org/wiki/Tag:surface%253Dgravel
Gravel roads have loose rocks which are impossible to ride on with narrow slick tires and challenging with wide tires. (now that I think of it's funny that gravel bikes won't be able to ride comfortably on what OSM considers gravel)

I've also added smoothness=bad.