Intent

They might not have been successful, but that isn't really the point:

'Martyr videos' of the type left by suicide bombers, were reportedly discovered on at least six laptops owned by some of the 23 suspects being questioned in the foiled airline terror plot.

The BBC, citing an unofficial police source, said that several of the videos had been found as part of the investigation into the alleged plot to bomb as many as 10 jetliners bound for the US.
Scotland Yard would not comment on the report, which came after police chiefs said that hundreds of officers from across Britain joined in the massive investigation, one of the largest in British history.

Last week, a US law enforcement official said that one "martyrdom" tape had been found by investigators.