Here is a provisional choice of one single strong advocacy of each approach (where an up-to-date presentation is available)
Obviously Loll at the Planck Scale conference.
Video: "Causal Dynamical Triangulations and the Quest for Quantum Gravity"
The last 12 minutes of Weinberg's CERN talk can't be beat.
Video: "The Quantum Theory of Fields: Effective or Fundamental?"
To save time jump to minute 58.
Don't have a video lecture. May not have one until November conference.
new look Loop
Waiting for the Corfu School talks to be posted online.
Hamber Regge QG
Hamber does a great job on PIRSA
Video: "Quantum Gravitation and the Renormalization Group"
Condensed matter approach
: geometry emerges from graph.
In my view, Fotini M. makes the most persuasive presentation. Not Wen exactly, but same general condensed matter idea.
Video: "Quantum Graphity: a Model of the Emergence of Locality in Quantum Gravity"
If anybody else can suggest other similar but better presentations of the same material, that are on line, please do. The idea is to have a minimal concentrated introduction to each one, so someone could watch all 4 or 5 talks and possibly pick one or several approaches as having more going.