Rebel T2i Gets Stuck in "BUSY" Mode After Recording a Video

Question

Hey! I've been recording video on my T2i for a while but suddenly, after recording a video, the camera would freeze in busy mode and then eventually shut off. I made a video explaing what is happening:
If anybody knows what I can do to fix this then please let me know.

Answer 1

The camera powering off on you is the firmware crashing.  
The on/off switch is really just a "software" switch.  It does not actually deprive power.  This is sort of like a TV and remote control... in that when you "turn off" a TV it's not *really* off... the screen is off and it's gone to 'sleep' but some part of it is technically 'on' and monitoring for a signal from your remote control.  The same is true of the camera and the power swtich... it's actually in a kind of extended 'sleep' mode.
When you open the battery door (or even eject the battery) there's a micro-switch that cuts off power.  That actually DOES turn the camera off (really 'off' because the camera has been deprived of all electricity.)  Inserting the battery and closing the door causes the camera to 'boot' fresh again... so the power switch (and everything else) will actually be monitored and respond as intended.
So what's wrong?  PROBABLY the memory card.  In nearly all of these cases with the stuck 'busy' problem it means the camera is trying to write your video clip to the card and for whatever reason it is not successful.  
I did notice you're using a SanDisk Ultra card (good).  How old is the card?
A few tips:  
ALWAYS format the card IN CAMERA (if you formatted a card while it was in your computer, then re-format it using the camera and pick the "low level" checkbox when you format it.)
I do suggest you perform a new in-camera format and make sure you check the "low level" option.
Memory cards do not last forever.  It's also possible you've got a dud (nothing is 100%).  The process of "writing" to a memory card is technically physically destructive (just a tiny bit) to the card.  Reading is non-destructive... you can 'read' from a card millions of times and never wear it out, but each time you 'write' to the card and change the charge state in a memory location you will have ever-so-slightly caused 'wear' to that location.  The card will eventually fail (all cards will).  But for most cards you'll get something like 100,000 writes before it becomes a problem (years of heavy use).  BUT... if you got unlucky and had a weak card, your card may be showing early signs of failure.  It happens.
I ALWAYS suggest you own more than one card (I have lots of them) and test with a different card.  If this is the only card you own, then you need to buy another card anyway because you never want to be caught without a spare card on-hand for just such an emergency.
Next... there are forgery cards on the market and some of them are amazingly good forgeries.  What separates your really nice SanDisk Ultra card from all the non-name unlabled "junk" grade cards ... is that your card has a really nice sticker on it.  It's not too difficult for a counterfeiter to print up a pretty convincing looking sticker.  I and several others here will tell you that it's not just enough that you bought a top-name memory card... you ALSO need to buy that card from a known reputable dealer to make sure you're not buying a forgery card.  Stated differently... I am unwilling to buy a memory card from a merchant I've never heard of before because they sell the same card I can get from a well-known merchant for $5 less.  Screw the $5... I want "known" quanity and that's worth far more than $5 to me.
This is not to say that YOUR specific card is a forgery... even SanDisk will just occasionally ship out a card that passed they're quality test after being manufactured... but just barely.  You get it and start using it heavily and the next thing you know it's showing signs of failure.
Could it be your camera?  Sure... it's just unlikely.
Occam's Razor (a well-established guideline for critical thinking using the scientific method) states that among competing hypotheses, whichever one requires the fewest assumptions should be selected.  
In your case the competing hypotheses are:
1)  The camera is failing:  Except that the camera doesn't fail at any other task... just this one particular task.  That's a bit difficult to explain.  
2)  The memory card is failing:  We've actually got well-established and well-understood failure of memory cards (a memory technology which will by it's very design WILL eventually fail.)  We don't need to apply many assumptions here.
As I mentioned above... you need another memory card anyway (every camera owner should have at least 2).  You may as well just start with that.
Good luck!
Tim Campbell
5D II, 5D III, 60Da