The interactions mostly use either

• Flash
• Director Shockwave
• Java
• Media player

All four may require some kind of free download, The first two from Adobe. The third isn't a browser plugin but it lets your computer run lots of cross platform programs. The last usually only applies to Windows and it usually comes with Windows.

Unfortunately at the time of writing the first two do not work with 64 bit browsers, but even 64 bit Windows machines come with a default 32 bit browser and Flash does work in these. In addition the free Director plugin did not used to install correctly on 64 bit XP or Vista machines. The first version that did was 10.3 and this had some bugs including adding lights to 3d models. There is some help here for versions priot to 10.3, should you wish to mess around with files and get it to work. It may also be worth looking at this.