My clips keep getting cut whenever i use the "Record what has happened" or "Start...

Go to your capture settings and change the record what happened to 5 minutes. If you press start recording it lasts way longer. Record what happened is for short clips only. Starting a recording has a longer duration.

Wait, you can use the "end clip now" under the Game DVR to get something that's already happened? I thought it was just to end a clip you had already started (and you still had to know what was going to happen in advance). I thought that the Upload app with
the "Xbox record that" voice command was the only way to record something that has already happened - or am I mistaken?

The shorter clips are automatically recorded by BF4 whenever you get promoted. Depending on what you're doing, I seen them range from 7 to 15 seconds long. I've had some clips not be recorded, start recording AFTER I said XRT, etc. I'm willing to let
the DVR issues slide (though not for long as it was a widely promoted feature. One, I might add, crashes my game), but not for long.

I have to agree with SirEzhno here, i mostly play fifa 14 right now and i am getting at least 5/6 auto recording per match.

Back in December there was an option in the system menu to stop the DVR from auto recording clips although "Xbox Record that" still worked and this stopped any auto recording, however once the April update came i started getting the pop ups again and this
time i can't stop it from happening. Whenever i want to use upload studio it goes slowly because there is about 200 "temporary" fifa recordings in my clips. I say "temporary" because some of them are now a month old and im having to manually go and delete
every clip which is simply ridiculous.

Please Microsoft allow us the ability to stop games from auto recording and uploading clips onto Upload!

The clip I recorded was recorded through the “record what happened” feature, using no external hardware. And between clips, no settings were changed