Whether those clips are actually scenes taken from future episodes or just promo clips, they have to be in accordance with the plot.

Regarding Glen, it looks to me that he is lying on the 2nd floor of a concrete building with walls blown off. Those walkers are on ground level, trying to reach up.

The only concrete building that has sustained that kind of damage should be the prison. So, perhaps after all the people in the bus are dead, he goes back to the prison. His using a lamp possibly means that he is inside the prison's dark corridors?

A less likely alternative is that the bus reaches a new town where Glen escapes to the 2nd floor of a building. The weak point of this theory is the collapsed wall status of such a building.

 

From those short promos, it looks like Michonne is ready to do some Prison Cleanup. Glenn's predicament is confusing to me, so is Daryl and Beth's. Why just pass out? I can't wait any longer for February 9th....