The notion of bundle gerbe is a categorification of line bundles/principal $U(1)$-bundles, and comes in two presentations: a linear version (with $Line_\mathbb{C}$-enriched underlying groupoid) and a principal version (using $U(1)$-torsors). It is really the first one that deserves the name "2-line bundle" (or line 2-bundle), and the second one "principal 2-bundle".
The concept of trivialisation of a gerbe is very much like the idea of a global section of a principal $U(1)$-bundle, and one also sees the analogue in the linear setting. However, line bundles may have global sections that vanish at certain points. Hence there should be a notion of section of a 2-line bundle (which would itself be some bundle-like object) than exhibits such a behaviour. Away from the points where the "section" vanishes, one should have a trivialisation of the gerbe by that data, but at the vanishing points the data should somehow be degenerate.
After that preamble, the only place I have seen such a definition is in a video of a talk at a German university (perhaps Hamburg) I started watching but gave up after prolonged buffering issues. The problem is, I cannot remember the speaker or the title or the conference! I think it was a graduate student speaking, but cannot after extensive searching figure out who it was. So my question is: what is the definition of a general section of a 2-line bundle, and what was the talk?
