You can not create a "ramped" reflection in Premiere Elements. Sorry. At least not without some very complicated work with the Track Matte.
Is it something that you could do with a series of still images using a transition from one to another? If so you might want to take a look at this Adobe TV tutorial: Creating reflections with Guided Edit
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I would explore using PiP (Picture in Picture), with a manipulated (likely something like Mirror) duplicate of your original Clip. Then, you can adjust its Opacity down, and likely use a few other Effects, like Corner Pin, and maybe even Ripple, depending on the surface that is reflecting. Last, you can possible use the Garbage Matte, or, as Steve mentions, Track Matte Keying to eliminate everything from that duplicate Clip, except the "reflection."
If you can post a screen-cap of one Frame from your Clip, and step us through what you want reflected, and on what surface you want it reflected, it will be easier to give you exact steps to do that.
Hi everyone, thanks for your advice. I've attached an image of what I am working with. The plan is to have two videos running at the same time. One video is a member of staff talking about some software, and the second video (which is a brief demo of the software being talked about) will then run after about a 10 second delay. I've managed to get all this working fine in Adobe Flash Catalyst, it's just getting the mirror to look like a reflection. I have sort of achieved a reflection look by creating a gradiented rectangle object and placed this over the top of the mirror (see my second image). Just not sure if there's a better way to do this at the moment.