In our daily work we see many different attempts to trick a user to install dubious software.  One of the more common variants is to use fake video codecs, in other words claim that the user needs to download and install their software in order to see some videos. This could look something like this.
As soon as the user enters the page they will be presented with the following warning:

If the user skips this warning and tries to view one of the movies the following will be displayed:

If the user skips this request to download too, a third attempt is triggered.

The user will now be presented with several security warnings and be urged to install various rogue security software.