This project seems to be dead, unfortunately, but I'll ask anyway...

The -o,--outdir should specify a different directory (from input file).
I'm using the ezthumb cli in a batch file (in a FOR loop, specifically).
I've tried everything to make this work: Backslashes added before and after, using quotes and double-quotes, even variable substitution. No success.
Funny fact: ezthumb is working indeed, giving proceeding output, even pretending to save the file in the specified directory, but everytime the file is not there.

The cur used option looks like:
--outdir \new\

Output of ezthumb is:

Name: vbt-bghsd1.mp4
Duration: 3:06:14 (1.76 GB)  1353.028 kbps
Video: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (Resolution: 720x394)   29.970 FPS 1226.845 kbps
Audio: AAC (Advanced Audio Coding): und 2-CH  48000Hz 121.573 kbps
522x284x20 Thumbnails Generated by Ezthumb 3.6.7 (23.541 s)
**OUTPUT: \new\vbt-bghsd1_thmbs.jpg**
MAGIC: SB HD M44 C3 M41 C2 U18 U23118 U14 U15 U15 U16 U13 U18 U17 U16 U16 U17

Edit: I've fortunately solved the issue! Tried once again all possible entries and suddenly it worked as expected!
Changes made:
--outdir \new\
to:
-o new\ (I swear I've tried this before...)

The specified dir did already exist, don't know if it would be created otherwise.