I think you're mistaking the normal stream update just released from BLU with Dev Preview stream.
I have two devices, one for myself and the other for my dad, and updated both through the Dev Preview to build v.8.10.14219.341 on Dec 12 and I still have the option for more tiles. I'm using three columns while my dad's is still on two columns of tiles.
Yes I found that this version is the GDR1 for 8.1. They did remove the 2 tile feature. Not a big deal at all. I have to say the people live tile is way too busy for me.
--john
Does this update fix the HD video issue? I have one wrapped under the Xmas tree for my son but was playing with it before hand and honestly can only play 1/2 the videos I clicked on, also the touchscreen would become unresponsive playing games (angry birds). don't know how Microsoft can market this phone when its pretty much useless with these issues...will return for a 635 if update doesnt resove it.
I installed You tube HD. I played some of my subscriptions in HD and they looked fine.
I can't speak to the screen hanging on games. I have not noticed it with my use.
--john