convert "file type:file" to mp4

[ghola]

I downloaded a bunch of vids using video downloadhelper.
Under properties some of them are "file type:file."
All of these "file" type will play fine in media player classic, realplayer etc.
I opened one in notepad and the first line started with "flv"
Does that mean it's an flv file?
I ask because freemake, realplayer etc cannot convert them. They can be played but not converted.
I'm trying to convert them to mp4 so I can view them on my roku via its usb port.
All of the other vids (mostly mp4) play fine on the roku.
I read that I can simply rename them? Is it that simple?

[jagabo]

Add ".FLV" to the end of your file names.

[ghola]

Add ".FLV" to the end of your file names.

thanks for the reply.
so then seeing "flv" inside notepad means it is indeed an flv file? I wasn't sure.
ok but why couldn't freemake convert it? flv is supported by freemake. or does it just need to read the flv at the end of the title?
sorry for my noob questions!

[jagabo]

Most video containers have easily identified structures at the start of the file. Indeed, the first three bytes of an FLV file are "FLV". Most media players will identify the container by examining the contents of the file. Most editor only look for the file name extension. Windows doesn't know what type of file it is (that's why it reports "file type:file") because it doesn't have the .FLV as the extension (Windows recognizes file type by the extension). Or you don't have an FLV reader/splitter installed.

[ghola]

Or you don't have an FLV reader/splitter installed.

I have no clue what that means but I will try adding "flv" when I get home.
thanks for your help.

[ghola]

that did the trick!
thanks again jagabo