The Standard Model uses two things: gauge theories (of which there are an infinite number) and symmetry. The symmetry tells us which gauge theory to use. In the landscape, the idea is that all gauge theories that are physical should be generated by the landscape. Each gauge theory then corresponds to its own universe with its own physics and fundamental constants.
The point is that starting from an arrangement of strings and branes, one can derive not just the Standard Model, but many, many different versions of the Standard Model. This would normally be a bad sign. But if we were looking for an underlying description of a multiverse, this isn’t a bad starting place.
The problem, of course, is that the string landscape makes a proposal that is inherently untestable. Not so, according to one of the speakers. And here we come back to the missing energy raised by one of the experimentalists. Missing mass could be due to large(ish) dimensions beyond the four we know and love, which could be taken as evidence for string theory. Or, as many other physicists will tell you, it could be evidence for alternatives. Either way, it will be a difficult job to analyze the data in such a way that the possibilities are narrowed.
Particle physics (and cosmology) have both gone way beyond my pathetic ability to comprehend them.