I've never used the USB slot in my Foxsat HDR PVR but just recently I wanted to view some video (wmv files) created by Picassa on my television. The video was too big to put on the only handy USB stick I had but I had a 150Gb maxtor USB drive so I copied it on to that and plugged it in to the foxsat. Although the foxsat recognised a USB device was inserted it could not read it stating it needed to be ext3, FAT16 or FAT32.
I could have formatted the disk ext3 from my Linux machine but I use this drive mostly on a Windows machine so I'd rather it was accessible from Windows (Yes, I know you can get ext2 drivers for Windows). So why wasn't it already formatted FAT32? Because it was formatted from Windows 7 as NTFS. How do you format a drive as FAT32 from Windows 7? There does not appear to be any options other than NTFS for format in Windows 7. After a bit of searching I found a tool for FAT32 on the verbatim site called SmartDisk_FAT32_tool.exe (I basically searched for FAT32 in their search menu). Bear in mind, FAT32 only supports files up to 4GB but that did not bother me in this case.
Copying the wmv to the USB disk and attaching it to the Foxsat HDR did not work - it does not see the file as something it can play. So I incorrectly guessed it need to be an MP4 file and went in search of a tool to convert WMV to MP4. I found Any Video Convertor, converted it to MP4 but the foxsat still did not recognise it. Then I thought I'd copy a video from the foxsat to the USB disk and see what it wrote. It writes 3 files (a .hmt [info], a .ts [standard transport stream format] and a .nts [index]). BTW, during this process I came across the FoxTab Video Converter (also known as Super) but be careful with this as unless you click advanced install it installs loads of other stuff including browser tool bars etc.
Some searching later and I found a program which converts an MP4 file to the 3 files the Foxsat needs (see My Humax Blog and AV2HDR). Downloading the AV2HDR-v1.6-win.rar gave me a program which converts the MP4 file to the required 3 files and hey presto, the foxsat now sees my video.
If you need video bigger than 4GB the following page will help - Transfering files from the Humax FOXSAT-HDR. However, none of these programs for Windows allow you to write to ext3.
I also found the following pages quite useful: