@Verloop Sure, it can be called it a stunt. Doesn’t make it less of an achievement in my view. I just preferred calling it that, especially vs the rather disparaging and condescending “hype”, but hey, to each his or her’s own opinion.
In terms of your questions, given it was clearly an attempt at breaking a record, the video and their spec sheet pretty much speak for themselves. Seems pretty obvious (but you’d have to ask them to be sure) that all conditions were optimal: hover with minimal movement, little or no wind, good weather as the video shows, max MTOW 25kg and no payload. (Their spec sheet lists 13kg empty weight with 20-25kg MTOW, and 2 hours flight time at max payload 5-10kg for Hybrid 2.1)
Btw the relationship between maximum hovering time and flying time with various payload weights is a tricky one, but there is obviously a definite positive relationship between them, laws of physics being what they are. More hovering time without payload implies more hovering time with. Same with hovering vs flying at speed (more hovering time without payload, more flying time with payload. (There is a slew of research papers on the subject).
Given the above, seems their copter with a relative small sensor payload (say <1kg, which is still plenty for many cameras and/or sensors ) and correspondingly less fuel could easily hover in excess of 4 hours in good conditions. But again you’d have to contact them to get better figures. That’s pretty impressive imo, and I can think of many applications: atmospheric observation and , area monitoring, data gathering, surveillance, etc …, basically anything where a tethered drone solution would be considered but would not be optimal given movement requirements or ground conditions. Same to some extent with flying at speed.
You can also contact them for more info. They are a cool company based out of Seville, Spain.