Trying to mount and recover data from a DVD/recorder HDD

I have a old DVD/HDD recorder (Panasonic DMR-EH58) with RCA inputs & outputs etc. I want to recover all the recordings off its HDD. The HDD is a 2008 ATA/IDE 7200RPM Hitachi deskstar Model no:HDP725025GLAT80 250 GB has a DVD drive. It has been used at a conference center for many years recording camera RCA input. It is in good condition but it is outdated so I am trying to copy the recordings to a computer. I also would like to recover the deleted files if possible as they would not have been overwritten yet. I have borrowed a universal drive adapter and tried to mount it on both Windows 8.1 and ChaletOS Linux (Ubuntu based XFCE type distro). Windows showed it as a grayed F: drive and Linux did not auto mount it either. GParted shows it as "/dev/sdb: unrecognised disk label": Command line attempts follow: joel@joel-laptop:~$ mount dev/sdb mount: dev/sdb: No such file or directory joel@joel-laptop:~$ sudo mount /dev/sdb /mnt/usbdisk [sudo] password for joel: mount: special device /dev/sdb does not exist joel@joel-laptop:~$ mount dev/sdb mount: dev/sdb: No such file or directory joel@joel-laptop:~$ ls -alh /dev/disk/by-path/ total 0 drwxr-xr-x 2 root root 160 Apr 30 22:05 . drwxr-xr-x 6 root root 120 Apr 30 18:41 .. lrwxrwxrwx 1 root root 9 Apr 30 21:31 pci-0000:00:1f.2-ata-1 -> ../../sda lrwxrwxrwx 1 root root 10 Apr 30 21:31 pci-0000:00:1f.2-ata-1-part1 -> ../../sda1 lrwxrwxrwx 1 root root 10 Apr 30 21:31 pci-0000:00:1f.2-ata-1-part2 -> ../../sda2 lrwxrwxrwx 1 root root 10 Apr 30 21:31 pci-0000:00:1f.2-ata-1-part3 -> ../../sda3 lrwxrwxrwx 1 root root 10 Apr 30 21:31 pci-0000:00:1f.2-ata-1-part5 -> ../../sda5 lrwxrwxrwx 1 root root 10 Apr 30 21:31 pci-0000:00:1f.2-ata-1-part6 -> ../../sda6 - Root directory is dev/sda5 - Swap is dev/sda6 - Windows is dev/sda1 - Spare data partition is dev/sda2 Looks like an unsupported file system error...