Sometimes the decision is down to the artist. Many artists agree to be broadcast on condition that only certain songs are aired. Occasionally an act may not wish to be filmed or recorded at all.
Sometimes the BBC is unable to broadcast footage due to regulations - for example, when material breaks BBC Taste and Decency Guidelines due to language, or due to it being unsuitable for broadcast before the 9pm watershed.
There are also decisions based on recording quality. The live nature of the event means the BBC or an artist may decide that the recording of a particular song is not of high enough quality to air. Excessive strobing can often be a problem for the BBC, due to OFCOM regulations about the broadcast of flashing images.
Rigging a festival stage for a large camera and sound recording crew is a complex and expensive technical operation. This means decisions have to be made about the best use of resources.
At T In The Park we are recording a selection of acts on the Main Stage, Radio 1 Stage, King Tut's Wah Wah Tent (around 50 acts in total) and the BBC Introducing stage (around 20 acts).
It takes time for our web team to process large video files.
Footage is received via satellite then transcoded to the correct format for publishing on the web. This takes processing time, particularly for longer videos. This is one reason why we try to provide a single track for each artist - it can be turned around more quickly.
The BBC receives a large number of comments across the weekend of the festival. Unfortunately due to this high volume we can only publish a small selection on screen. We select tweets by following #bbctitp or reading replies to our official Twitter account.