Sensor detects light coming in through the camera lens.
Lens picks up light from what you point it at.
The sensor is made up of lots of receptors which are turned into light values. Sensors converts the light into electrical signals. The more pixels the more detail the sensor picks up.
The electrical signals are turned into binary values 1 and 0 and this allows it to be stored in the computer (binary on or off)
The digital values are stored as files.
Videos create a lot of data and we want to keep the file sizes as small as possible. To do this we use compression.
The software that compresses a file is known as CODEC.
You can get different types of Codec which relate to different file language.