I need to know that can I get small videos which can be used as training guides. for example how to create SO or How to create Item/Product AX 2012 R3?
You can find some videos attached to processes in LCS Business Process Modeler. You can also record your own processes (including video) using Task Recorder in AX.
Youtube is a great source
e.g. https://www.youtube.com/watch?v=58hFxD6XwrI
Are you able to login to ms partner source? There are many many many training videos.