Well, it has been a few days researching on a suitable auto or semi-automatic way of mass merging files this way. Basically, what I want to achieve is inserting the same clip, before a bunch of other clips.

In this case I´ve been trying with .flv, .mp4, .avi files (always merging same codecs), and I didn´t succeed after testing **all the programs available** in both Windows and OSx. Believe me, I´ve tried them all. The only ones which are supposed to handle quite well this quite of tasks are from Videocharge: *Watermark Master* and *Videocharge Studio*. None of them could perform correctly the task. 
Maybe there was some way I could have achieved this by scripting with *After Effects* or *Sony Vegas*, I just didn´t find any.

Now I´m trying to find some way to achieve the same thing either by shell, unix scripting... I don´t care. I just don´t want to mount Ubuntu only for these tasks. I´m not a programmer, but I´m quite stuborn (which sometimes leads me to neverending nights) so I would appreciate some help or guidance from anyone keen and good enough on batch video processing or scripting.

Right now, the only useful paths I´ve found drive me into either using **mencode** or **ffmpeg** through commands, but I am not able to perform the merge on batch.
I don´t care about the way to sort the videos out. But taking into consideration that the operation would be performed on hundreds or thousands of videos, it wouldn´t be suitable to have them all in separate folders each accompanied by the "unique" intro clip. I guess that the most logic way would be storing the "bunch" videos in a folder, and the intro clip on the same folder as the encoder or renderer.

Thanks in advance for any help or guidance,