Why am I getting these error messages when I try to view media files on my Android device?

The error which was clearly shown is, Unable to mount MTP device. So your system fails to mount(open) this mtp device. Installing mtp-tools package will solve this error and makes your mtp device to get connected.

sudo apt-get install mtp-tools

Resolved this issue by upgrading to Android 4.4. Now, when I plug in the device, I get an "Android" device in Nautilus, which has two separate drives available, my internal and external SD card. There are no interface actions on the phone needed to connect the device. I actually can't tell if it's connecting using MTP or USB mass storage or what, but so long as it's working, I'm not too concerned about it.

Media files don't have preview icons, but can be opened and viewed without any errors.

On my galaxy s3 (android 4.4), I changed my settings from Media Device (MTP) to Camera (PTP) and I was able to view my Pictures and others files just fine.