gamevideos.com server is restrictive when it comes to referrer header. You can't request flv with referrer from other domain. You must send either no referrer or gamevideos.com one (didn't checked this one).
When you press play, flash player requests flv file: +++GET 17+++
GET /8021/gv.com.BrokenPixels_005_320x240.flv HTTP/1.0
Host: download.gamevideos.com
User-Agent: Opera/9.10 (Windows NT 5.1; U; en)
Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1
Accept-Language: pl-PL,pl;q=0.9,en;q=0.8
Accept-Charset: iso-8859-1, utf-8, utf-16, *;q=0.1
Accept-Encoding: deflate, gzip, x-gzip, identity, *;q=0
Referer: http://zajec.net/bug/flash_player
Connection: keep-alive
+++RESP 17+++
HTTP/1.0 302 Found
Date: Sun, 17 Dec 2006 17:56:03 GMT
Server: Apache/2.2.3 (Unix)
Location: http://www.gamevideos.com/
Content-Length: 296
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=iso-8859-1
+++CLOSE 17+++
Server does not send flv file in response because of referrer header which Opera sends.
Using Fx and IE, server returns flv file thanks to missing referrer header: +++RESP 19+++
HTTP/1.1 200 OK
Date: Sun, 17 Dec 2006 17:57:01 GMT
Server: Apache/2.2.3 (Unix)
Last-Modified: Sat, 16 Dec 2006 06:57:59 GMT
ETag: "5e8000b-4738d85-44ceebc0"
Accept-Ranges: bytes
Content-Length: 74681733
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: video/x-flv