BBC Documentary on the British

The BBC 2 documentary on now talked about British speaking Picts. This is compared to the Irish speaking Scots. Now I guess the Scots spoke with a Celtic / Gaelic language but what is the British language they said the Picts used? I thought Brythonic was a British language of past which is a type of Celtic language like Gaelic what is the documentary on about with the language of the Picts?
I'm.sure someone knows.something abt this. Pretty knowledgeable folk around here at times.

Are you sure they didn't say Pictish? The Picts spoke a language which was distinct from Gaelic (as spoken by the Scotti) or Cymraeg (Welsh) as spoken by the indigenous people of Rheged (Cumbria, part of North Yorkshire, Dumfries and Galloway) and Strathclyde in early mediaeval times.
In the Iron Age, Pritennic was proto- Pictish, Goidelic was proto-Gaelic and Brythonic was proto-Welsh.