Approximately 1 minute into the video, the blonde girl finds her partner with another girl in bed. The blonde girl's reaction is made clear by her facial expressions and body language. She throws pillows and is very active. Due to this, it is clear they are having an argument even though you cannot hear the actual conversation. The lyrics are about cheating on a partner which also enables the audience to understand what is going on in the video. This is why it is unnecessary to hear the dialogue. The lyrics in our song, Watercolour by Pendulum, indicate desperation which is related to the protaganist taking drugs. There is a clear view of the drugs being exchanged which is why the scene doesn't have to be explained through dialogue.
Other examples of a music video that contains a sequence where dialogue is not heard is 'Bittersweet Symphony' by The Verve and 'Radio' by Alesha Dixon. These can be viewed on the links below.