What you are seeing at the bottom of the screen (of your Legend) is part of HTC Sense (which you get on all HTC phones). The videos you saw of FroYo were probably on phones like the Nexus One which are essentialy a pure Android experience - no additions to the user interface from third party manufacturers - like HTC.
Prior to FroYo you could switch to the default Android launcher and experience what users of the Nexus One get - no Sense.
But now (FroYo) you are stuck with Sense, unless you install an app called Launcher Pro which allows you to run home screens that look similar to what you saw in the videos.
As far as I am aware, if you switch to Launcher Pro you won't be able to use you HTC Sense widgets though.