May you please elaborate to provide troubleshooting info by going to Firefox > Help > Troubleshooting > Copy to clipboard button and paste it there

Thanks in advance!

Sometimes the extension is not included during the upload / posting process. Likely the fault of the up-loader. What you can do is edit the file and add an extension. AVI, MP4, WMV, FLV are the most popular types. Just use each in turn until you get the right one. Some players may tell you that the file format does not match the file type, but will try to play the file anyway.

You can rename the file and add the missing file extension.

Also check that there is a file extension showing when you download and save a file and add one yourself if it is missing.

• Tools > Options > General : Downloads