Pros and Cons of Undergravel filter design with bottom drain hole

[Rosegardener]

In this video, the designer deviated from the age old undergravel filter (UGF) with:

1. Bottom drain to extract waste under the UGF, most ponds have one of them. Having that drain hole could be a pain as leaks could happen, but it also eliminated one of the biggest complain about UGF ie gathering of waste under the plate.
2. The filter was more elevated from the tradition UGF, almost 1 inch (2 cm?) Probably need more water movement as more water will be under the plate? May be powerhead?
3. A felt like sheet between the filter and gravel.

Thoughts?