slowmoVideo video is the thing!
Playing around with an open source project named slowmoVideo, the initial footage is taken from Gopro’s in setting 4 (1280×960 39fps). There is also a flow-editor included that can help removing artefacts from the video, but i didn’t bother for that clip. So this is a free and really good alternative to the rather expensive Twixtor plugin (350$-700$ depending on platorm and version).
The downside is that you need a Linux box with a Nvidia graphics card to work with it (Mac and Win ports are under development), and you should know how to compile something yourself on it. I also would recommend a fast CPU since render times are quit long.
If a walkthrough on how to setup and use this whole thing is wanted, just let me know.