What you saw was most likely a Focus Attack Dash Cancel.
All specials that can be super canceled can also be EX Focus Cancelled (people usually leave out the EX part when talking about Focus Cancels). This consumes two EX bars and causes your special to skip all recovery and immediately go into the charging of a Focus Attack. It is possible for many characters to release the Focus Attack and continue the combo, but most people will simply Dash Cancel the Focus Attack immediately (this is referred to as “FADC”) and do another attack, usually an Ultra.
In order to do an FADC, you simply have to input a Focus Attack (:mp:+:mk:) just as your special hits, then dash either forward or backwards to do the Dash Cancel.
Due to the way inputs are handled in SFIV, it is possible to do the Dash Cancel using only one forward/backward input. This is possible because the game remembers your forward input from the special move, so when you do another forward input after the Focus Cancel, the game recognizes that you have done the two forward inputs necessary for a Dash Cancel and does it. Of course if you need to dash backwards, or if your special move didn’t have a forward input in it, then you will need to do the dash with the usual two inputs. This is important to remember, otherwise you might do too many forward/backward inputs and get two dashes instead of one, which will usually lose you your combo opportunity.
So, if you wanted to do LK Cannon Spike xx FADC, Spin Drive Smasher, it would look like:
If you wanted to do LK Cannon Spike xx FADC Backdash, LK Spiral Arrow, LK Cannon Spike, it would look like:
:dp:+:lk:,:mp:+:mk::l::l:, :qcf:+:lk:, :dp:+:lk:
(you can also do :l:+:mp:+:mk:,:l: instead of :mp:+:mk::l::l:)
Remember that you can only FADC special moves that could be super canceled. In Cammy’s case, this means you cannot FADC her Cannon Strike or her Hooligan Throw.