Why can't I download and play my videos on NOOK Tablet

Why can't I play my videos on NOOK Tablet?
So I downloaded android video players "MoboPlayer" and "MX Video Player". Which actually play any format, because it says it does. My videos are in .avi format, so I thought it would work like VCL. When I go to play a video on either of the player apps. It just goes to pay it for a split second, and then goes back to the selection screen. It refuses to play for some reason. Whats the problem here? Help me please.

All this videos need to be put into Nook Tablet, if it is Mp4 format then no problem. If i other formats like FLV, F4V, M4V, MKV, AVI, Xvid, RMVB, WMV, DivX, 3GP, MOV, VOB, MTS, TS etc you'll need a professional Video to Nook Tablet Mp4 Converter Mac to convert any videos to Nook Tablet Mp4 and playing it on Nook Tablet with best quality.

load a microSD into a card reader and copy/paste them into the card. Then use the card into the tab. But remember that they reserve that space for apps and books plus the OS. You can only use 1GB of 16 GB for your own music, videos, etc. unless you add a microSD.

If you has this converter so you can use it often after convert a video to Nook Tablet, delete it and convert another video to Nook Tablet. So you will use the converter much.

Step 1: Click "Add File" to load videos from your PC Hard Drive to the program.

Step 2: Set Nook Tablet Mp4 format.

Nook Tablet supported format: Watch videos in MP4, or Adobe Flash Player format, 3GP, 3G2 MKV, WEBM (Video Codecs: H.264, MPEG-4, H.263, VP8) renders at 1024 x 600 Play audio on built-in mono speaker: MP3, MP4, AAC, AMR, WAV, OGG (Audio Codecs MP3, AAC, AMR, LPCM, OGG Vorbis)

Choose 720p for Nook Tablet(recommend setting)

Step 3: Click "Start" button to begin convert video to Nook Tablet MP4.