As suggested by adicoto, please list here the filters used to decode your movies (with movie loaded -> right-click -> Options -> Filters -> Advanced)
Plus, if you enabled v-sync, try to disable it (CTRL+P -> Video -> Video rendering -> <disable> Wait for vertical blank) and see if this small jumps still occurs..
Please, if you can, next time use only English (this is an English forum and many users don't know French) or write both in French and English, for example:
Salut, comment ca va aujourd'hui?
Hello, how are you today?
