I'd say:
1. Learn that Adobe Flash is non-free and sites asking you to download it don't know or don't care about software freedom.
2. Learn that SWF format is not a free format, so why perpetuate its use?3. Remove Gnash. It's only for SWF files. I thank Gnash developers for the good intentions, though.
4. Be patient. HTML5 use is growing and growing.
