Fiberglass Reinforced 3D Printing?

We ran across what appears to be an experiment by remote control flyers who are trying to hack super-strong airplane parts. The video doesn't really explain what's going on, but it appears that they might be trying to sandwich some strong fiberglass fabric within a 3D print. If so they'd have to design their model appropriately and then somehow slip the fiberglass onto the print as it takes place. 

 

Maybe someday we'll be able to print fiberglass on a second print head and this would be quite a bit easier. 

 

Via YouTube and RCGroups