Well, I tried a few things today and think I have found the solution.
Apparently the .26 firmware update which "fixed" large sized MicroSD card support still needs some work on the Asus TF700.
I have the 64GB SanDisk Micro SDXC Ultra class 10 (mouthful) card which apparently as of yet is not fully compatible. I did try reading from my PC which worked fine, then i tried to copy the file from the card to the internal memory of the TF700. This failed. I then tried a few other means of moving it around, all failed. I formatted the card exFAT, NTFS, FAT32 and tried unsuccessfully FAT. All loaded the content fine but would not play in BSPlayer or move it to internal storage. Clearly this is an Asus issue.
I will say this, my write speed with FAT32 and exFAT was around 8Mbs, with NTFS it was just over 100! Im returning the card and ordered a new class 6 that is supposed to be more compatible based on some info I just read on this thread:
Micro SD Card List - Page 10 - xda-developers
Thanks for your help, hope this helps someone as well. I will be purchasing the full version shortly.