Short documentary in german about Synaesthesia. Looks like a home-maid documentary (bad video quality), but the protagonists gives a couple of good examples to explain his special perception.
E.g. waking up in the morning by a flashy yellow (!) sound of the alarm-clock.
He also describes some positive effects of synaesthesia, for example as a helping tool for learning or remembering stuff (“he had a blue name…!”).