I have been testing my theory out the past few weeks. I was seeking to find out if signal had much to do with Youtube App working, or in our case, not working. I also think it might have to do with signal strength vs buffering time and/or memory.
I have tested thoroughly using WIFI vs 3G.
I selected a short list of videos that I watch. Mostly Monster Jam Clips, and compilations of monster truck related crashes and races, etc. My 2 year old loves these things, so we end up watching them quite a bit.
These videos range anywhere from 30 seconds to 6 minutes.
Using WIFI, and a strong signal, watching in High Quality, I found videos working almost all the time. I would say a good 90% of the movies work the first try. If I try to watch a "related video" after the movie ends, it drops down to about 50% chance of it working at that point. Upon re searching for a new movie, the percentage goes back up to 90%.
Using WIFI, weak signal. and HQ, results went down to about 50%. However, switching to low quality brought it up a bit, but not much. Probably 60% or so.
Using 3G only, High or low quality, the results are basically 0-25%. I notice that when I have stronger signal strength, the videos will play more often. But it is still very low success rate compared to having WIFI enabled.
I would suggest that everyone try to use WIFI as much as possible. Please try and test out these scenarios for yourselves and report if you find similar results. Not a perfect solution by any means, but a good work around until we can do better, or an update can fix it.