How to demux a FLV MKV

Season Greetings, Experts.

I have  a file with the .MKV extension.
It plays alright using Media Player Home Classic.
Using mkvmergeGUI, I tried to demux/remux the file.
But encountered a problem loading it in mkvmergeGUI.
It throws up an error message, "The file is an unsupported container format (Macromedia Flash Video (FLV))."
I did not realise that FLV is not just a video format, but a container as well.
In this instance, is there a way that I can extract the FLV from the mkv container, convert it to say MPEG or AVI, before remuxing.

Thanks, Experts.
garychuAsked:
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☠ MASQ ☠Commented:
David Johnson, CD, MVPOwnerCommented:

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MereteCommented:
Drop this ,mkv on to Gspot ( codec analyser) so you can determin what is in this mkv.
http://www.videohelp.com/tools/GSpot
Once you know what the internal codecs used are then post back to detemin the next step
FFDSHOW
Description
ffdshow is DirectShow and VFW codec for decoding/encoding many video and audio formats, including DivX and XviD movies using libavcodec, xvid and other opensourced libraries with a rich set of postprocessing filters.
http://sourceforge.net/projects/ffdshow/
http://www.free-codecs.com/download/ffdshow.htm

It could be the cmd lines your using, if it helps
A guide to mkvmerge GUI (mmg)

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garychuAuthor Commented:
Thanks, Experts for coming to the rescue!
This is what I did.
I tried FLV Extract. It would not allow me to drop the MKV file into its gui. (Maybe it only allows .flv files).
Next, I tried GSpot as suggested.
The result was the following;
screenshot of gspotThe result was not entirely helpful for me.
Then I tried HandBrake. It allows me to successfully convert to an MPEG4.
Using MKVMergeGUI, I was then able to add it to re-mux.
In spite of the convuluted process and the time it took me, I was happy for the educational value of the exercise.
Thanks again.
Merry Christmas and a Happy New Year!
☠ MASQ ☠Commented:
In hindsight you might find EnrightSoft's SUPER useful for this too. In the main window switch the radio button on the top left from the top to the bottom one to use the GUI for Demux/Remux. (Just in case you have a different file format in your FLV container in future)

Seasons Greets!
MereteCommented:
Good to see you resolved it garychu, going on the Gspot analyses there was some unknown codecs used to create the mkv or you don't have any codecs suitable installed.
Gspot uses the codecs you have installed.
Handy tool anyway.
Here's an example of one of mine mkv just for your information
Merry Christmas to you and yours
MKV on Gspot
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