As well as being able to show the connection between similar or identical topic image sets and video clips, WACS can also offer a choice of various difference versions of the same set. Most usually these choices are based upon the dimensions or quality of the images or video and thus their physical site as a download.
On we usually offer two versions of each video clip - the High Definition one for people with a fast MediaCentre style PC - and a Standard Definition (DVD-sized) one for people with a more modest PC, SmartPhone or more modest download speed. Here's a set information page for one such video showing what is available.
The main point of interest is in the box in the middle, towards the bottom of the screen where it provides details of the two versions of this movie that are available - the massive 672MB High Definition version and the smaller 530MB Standard Definition version. This gives you the choice of which of these two versions you wish to download. This particular page is for the HD version, but of course you can click on the link to the other version for the smaller SD version. In addition to this you can see a link to the matching photo set.