I'm currently using Camtasia 1.2.0 on Mac. I know there are still quite large differences between the Mac and Windows versions (in fact I don't think you can open the .cmproj file created on one platform version to the other - this was certainly the case previously).
In the Mac version we use:
Share > Advanced Export... > MP4 > Options > and then click on the 'Streaming' tab
Because menus are different between the Windows and Mac version I'm not sure it will be in the same place, but you should be able to hunt around for it, or maybe search for streaming in the Help files
On the Mac version choosing 'Export' there is also a box for generating the HTML required to embed the movie on a page