Below are some good links to keep and read... as for your current problem, I do not try and work with files that are designed for web playback, so can't help
Online User Guide http://help.adobe.com/en_US/premiereelements/using/index.html
-Page to download current PDF http://helpx.adobe.com/premiere-elements.html
Importing Video http://forums.adobe.com/thread/1065281
-and project settings http://forums.adobe.com/thread/1112086
Saving & Sharing http://forums.adobe.com/thread/1137128
-Sharing to DVD or BluRay http://forums.adobe.com/thread/1137645
-Sharing for Movies http://forums.adobe.com/thread/1051093
-Sharing for Computer http://forums.adobe.com/thread/1058237
Steve's Basic Training Tutorials... steps are the same for several versions
-start at http://forums.adobe.com/thread/537685
-be sure to click More Results at the bottom of the "tv" page
Welcome to the forum.
FLV's come with several internal CODEC's, with Sorenson Spark and On2VP6 being two popular ones. PrE can Export FLV's, but Import can be an issue, just as you found. I have several products from Moyea http://www.video-to-flash.com/products/ including their old PrPro FLV Importer Plug-in, that was for versions of PrPro, before about CS 5. I know of no Moyea product, like that, for PrE as the hosting app., but they might have added one. I use their FLV Converter, and also the free FLV to AVI Converter, if I am not using my older PrPro, with the Moyea Plug-in. Both of those converters have worked well.
Maybe others have some useful ideas, or recs. for you.
I'm with Bill. You can not use FLVs as source files in a Premiere Elements project.
The Moyea Importer for Adobe Premiere Elements was the answer to your situation for Premiere Elements 8.0, 7.0, 4.0, and 3.0
However, I do not believe that it has served that purpose for versions of Premiere Elements later than version 8.0.
For your convenience, I just downloaded and installed this plug-in. Still works for version 8.0, but does not for 9.0/9.0.1, 10, or 11. That is what I found with first hand look at this just now.
Thank you for that verification.
As more of my work is in PrPro, I knew about when the Moyea plug-in ceased to work there (I keep an older version around, when I need to use FLV, and a few other formats/CODEC's).
I did not have any PrE versions, between PrE 4 and PrE 11, to test with.