Help? Flash Move / Website Demo - Software Recommendation?

Many moons ago, I went to school for digital media design. However, I don’t do much of any development work any more (it’s been possibly 10 years since I last loaded flash) and am looking for some help.

I want to add some demo movies to one of my websites, kind of like the movie on this page:

Sample Movie

What would you use to create this movie? Would it be Adobe Flash? I did a bit of googling and it would seem that HTML5 is a new standard, some websites mentioned smokescreen, lightspark and gnash. I would just like to konw what software is popular for creating a reasonably simple demo movie?

I know there are at least a few developers on this forum, hopefully one of you can jump in and point me in the right direction. FYI, open source software is preferred, but if the pay version is significantly easier to use pay software is fine too, depending on the price. Any advice?

Thanks in advance!