OT - "Find and replace in Windows 7" - how do I do this?

[tigerb]

I've about 300+ video files in .f4v that my Samsung TV wouldn't play, however if I changed the ext/file name to either .mp4 or .mkv then the Samsung TV would play them 100% of the time.

If I'm to do this one by one using Windows default way, I would be prompted each and every time if changing the file ext would/might render the file not playable and I have to "OK" each and every file....

Is there a better way to do this? basically all I want is to have all my files ending with ".f4v" to be replaced with ".f4v.mp4" (I want to keep the .f4v before the .mp4 so that I know the original file ext).

Example:
"Find" all ending with .f4v

abc.f4v
bbc.f4v
cab.f4v
ddd.f4v

"Replace"
abc.f4v.mp4
bbc.f4v.mp4
cab.f4v.mp4
ddd.f4v.mp4

Thanks.

[Baldrick]

From the command prompt(cmd) type

rename *.fv4 *.fv4.mp4

in the same folder as the files. (type cd "c:\folderwithfiles\" to go to that folder first)

[tigerb]

From the command prompt(cmd) type

rename *.fv4 *.fv4.mp4

in the same folder as the files. (type cd "c:\folderwithfiles\" to go to that folder first)

Thanks Baldrick, simple and yet powerful!

Have a great day!

[Baldrick]

It's night here. . Zzzzz.