At some point towards the end of the clip (04.27), though, he states that
“in informal speech the /t/ sound is often replaced with the glottal stop when the /t/ sound is at the end of a syllable and the sound before the /t/ sound is a stressed vowel sound, or a syllabic /l/, /m/ and /n/ sound and the next syllable or word begins with a consonant sound.”
Before syllabic /l/, /m/ and /n/? In informal speech? What language is he talking about? And did you notice how he pronounced the adjective syllabic? ˈsɪləbɪk. I must admit it is the first time I’ve heard this type of pronunciation!
And here’s another example he furnishes:
“It’s pointless becomes it’s poinʔless because a glottal stop replaces the /t/ sound after the ˈsɪləbɪk /n/.”
Quite connected with the above is the pronunciation used by BBC reporter Raphael Rowe. According to information provided by the BBC, Raphael
“was born and brought up in south-east London and he joined the BBC in 2001 as a reporter for the radio news programme, Today. His tone, style and accent was different to that normally heard on the flagship programme and caused an immediate stir amongst the Traditional Radio 4 audience. But Raphael’s path to becoming a reporter has been unique and remarkable indeed. [...] Through his singular background, and as the first person of mixed race to report for Today, the Six O’Clock News and now Panorama, Raphael has helped re-write the rules on what makes a BBC reporter.”
Here’s a video in which Raphael introduces himself and talks about what it’s like working at Panorama. Notice how he produces glottal stops in getting, bottom, curiosity, reporters, presenters and democratic. This is of course admitted in his accent but not (yet) in RP.
Finally, here’s a short video of the Panorama programme Track My Trash, broadcast last Sunday night on BBC World News and on Monday on BBC One. As I was watching the programme, I couldn’t help noticing Raphael’s realization of gathering as ˈɡævərɪŋ (at 00.04 in the clip) and of thumb pronounced as fʌm (00.53, 0056). These are clear examples of th-fronting, a phonetic effect typical of the broad accent of London.
Also, if my memory serves me well, he regularly pronounced system as ˈsɪstɪm rather than the more common and (at least for me) less old-fashioned ˈsɪstəm.