Indeed in a Yes/No situation where you have specific instructions for one of the branches, but not for the other one, to avoid that the play head just stops (http://blog.lilybiri.com/why-choose-standard-over-simple-action) you sometimes need to add Continue.
Custom: not really, you can change And to OR on any line, but because you cannot use parentheses, you have to be very careful and test thoroughly if such a combination is working as expected. Mostly I prefer to create more decisions.
You must have misunderstood about nested advanced actions I think.
For webinars, go directly to the Adobe site: http://www.adobe.com/cfusion/event/index.cfm?event=list&loc=en_us&type =&product=Captivate&interest=&audience=&monthyear=
The webinars that have still to be presented are on top, and have a register link, those On Demand are below. The one I presented yesterday is not yet posted. For the other ones you'll have to scroll down a lot, they are also in the list for which you have already the link, look under Advanced actions topic.
Lilybiri