misspellings in source strings

During translation of the module I found some misspellings in the source strings:

Video transcoder will help you to video conversion and automatic thumbnail generaion. (generaion -> generation)
Path to save video thumbanils extracted from video (thumbanils -> thumbnails)

In

If you want to use default image instead of using actual thumbnail of video then check.

I suggest to write 'use a default image'.

Overall there is a mismatch in the option strings that are used: most of them are written with the first letter in uppercase (such as 'Path to Video Thumbnails') whereas others are in lowercase (such as 'Video thumbnailer options'), sometimes it's inconsistent within one string (such as 'Destination video Width'). Looking at other modules lowercase seems to be standard.