Another trailer for the Special, which I thought I'd posted. Apparently not. Via @Sherlock221B [link masked due to spoiler-dialog].
Sherlock Special Panel at MCM London Comic Con - Sherlock published on Oct 30, 2015 -- this is about 10 minutes or so into the panel, from what I can tell. Volume isn't too hot, btw.
Only about the Special's title and air date.
Overlapping, longer version of Sherlock Special Panel at MCM London Comic Con from Flicks and the City. I bet this has spoilers, or at least teasers. Don't know why I'd think that!
Volume is variable, alas.
Sherlock Panel - Nerd HQ: Comic Con 2015. Published on Jul 11, 2015.
"Sherlock" Interview at Comic-Con 2015 - TVLine: Rupert Graves, Sue Vertue, and Steven Moffat. Published on Jul 10, 2015.
Happy Birthday @JohnFinnemore ☺ I wish you all the best for the upcoming year! Thank you for #CabinPressure ♡— Tanja (@Lacrima87) September 28, 2015
Alas, I completely missed this. But I've been meaning to tell YOU, so you know about John's birthday for 2016. :)