Gents, the TV will format your Hard Drive with a Linux file system that Windows will NOT recognize. You may be able to read your files on a Linux machine.
Samsung Smart TV's will read files on a HDD formatted as FAT32 or NTFS, which is my preferred choice for larger file transfers. I run Macs and with Tuxera software can read/write all Windows formatted drives. Files play seamlessly using a portable HDD formatted in NTFS for me.
Things you must consider are:
The file extension; The TV will play all mp4 files as long as the .extension is .mp4. It will not read iTunes protected .m4v files or other protected files.
If the files are in .m4v (or any other mp4 compression, avi ,H264, etc., which are all mp4, then you only need to change the extension. No need to convert large amounts of files. There is software available to do this in batches. I have done this with 2 TB of files and all play fine.
USB Port on TV; Samsungs have 2 USB ports, one being specifically labelled for HDD, with the power to run portable hdd and be recognised by the system as a drive. The other USB port you use to run/charge peripherals.
I have run both portable and powered drives this way.
Recording from the TV is a different story. ; to record to an external drive the TV will need to format the drive in Linux. In which case all other data is lost. The format is either ext2, ext3 or ext4, quite old formats but used by Linux systems and able to (somehow) hold extra data.
You therefore can't have the same drive for playback and recording. choose one or the other.
Oh,... while Linux Reader might work on Windows, good luck finding an equivalent for Macs.
I am able to edit recordings made on the ext3 formatted drive but it is a long process and requires a Linux laptop, a Windows formatted drive, conversion software and a lot of patience.
Hope this helps a bit.