Some video files contain tag data and MC can read them. If no tag data is available, MC uses filename as video name. I do not know why you get those names. Could your ripping software put those names in the file? I am not sure if it is possible for avi files though.
As for VIDEO_TS, it should work, i.e. MC should get the folder name as the movies name, instead of VIDEO_TS.
There are various ways of changing the name field (as well as other fields) depending on the view you are in. For example you can choose "Tag" from the Action Window, which opens up a Tag window. Find "Name" field and edit it and then close the Tag window. The Library tool "Rename, Move, & Copy Files..." is for renaming filenames, not for renaming the Name field. The Library Tool "Fill Properties From Filename..." can be used to rename fields.
