Several workarounds have been proposed.
- If you are using firefox, get the User Agent Switcher addon (extended Ubuntu forums discussion) and set it up as a friendly participant suggested. This solved my problem for the moment.
- If that doesn't work for you, get the *.mov file's address from the page source code and paste it into a new tab, as described here. I didn't get the "Get the latest Quicktime" message though, so I couldn't try this.