Always use the best tools for your needs. Sometimes, unfortunately, PG isn't going to be the solution. If your goal is to write 90% cross-platform code, you're going to have to do without using custom plugins -- the plugins are understandably native and in totally different languages. If all you have to do is write a plugin that interfaces with a Video Conf API that exists on both platforms, that would be /easier/ (most of the work will be done for you -- you're just writing a wrapper). But if not, you may as well go native, personally. Unless you can do 100% video conferencing in HTML/JS/CSS... Who knows... canvas can do some pretty cool things... why not that? (I really don't know if it is possible... I'm guessing it would be more painful than going native, though...)
If you can wrap around a pre-existing API, try it. If you have write a lot of custom code, might be better to go native from the start.