Help please.

Although the Sync function works well for "Music - Sync all Songs and playlists" for copying stuff from my I tunes library to the Ipod ......

the same does not apply to "Movies - Sync All movies".

The "Movies" in my Itunes library consist of some 200 short clips - mostly
Utube clips converted to MP4 format.
They transfer ok but whenever i reconnect my Ipod back to the PC, the Ipod program will either
1) show the Music tab and not the Movies tab (pretending that my ipod does not hold any movies) or
2) proceed to wipe off all the movies on the Ipod and then display the Movies tab with "Movies - Sync All Movies now unticked!!) as if some gremlin is unticking that box.

Is this a normal feature of Ipod?

Why can I not "Hold" the "movies" on the Ipod and add/edit by sync to the Itunes Library?

Can you help please?