Military Push Ups to Failure

I do a lot of exercises to failure, but realized that I always stopped short of failure when doing push ups.  There can be a suprisingly wide gap between when I think I'm going to fail and when I actually do.  In this case, I would have normally stopped around 55 but instead completed 63 to failure.  I think the last few were harder mentally than they were physically.

On a side note: push ups are relatively new to me, and I had previously been doing a wide grip push up and was told that I should be keeping my elbows in closer to my body.  This was A LOT harder for me.  Is it supposed to be harder?  In this video I'm trying to use a more standard form by keeping my elbows in.  You are welcome to provide a constructive comment on my push up form, I am by no means an expert here!