That banner was added because there's a bogus LW update showing up in search results. It's a 75.7 KB .exe & shows up as "Urgent LW update - download & install now". If people download & install that thing they could end up infected. So, to make sure everyone knew that it was crap, the warning banner was added.
It's just to make sure everyone knows what's a real LW update & what's not.

The padlock symbol doesn't apply to music or video etc