What technique does this stream-player (globaltv) use?

[vel_2000]

I just downloaded a demo version of this player.
It's used to stream german Live-TV
https://www.globaltv.to/download (the sd version with 5 channels for testing purposes)
This player downloads fragments from a server and re-assembles them.
This seems to work very good.
Does anybody know, what technique, downloader or player, is used?
I've attached a debug-info.txt, that I found

[vel_2000]

really nobody?