Need Help with Joining After Editing

Hello WinstonSmith6079,

You can try to use some additional software to change resolution of some video file.
Here you can find some useful tips on how to do that:

http://www.online-tech-tips.com/computer-tips/how-to-resize-a-video/

After that you can try to join files. Please note that all parameters including video, audio content, width, height, bitrate should be same for Join Manager can merge these files.

Ah, boy!  I had the problem again, a little differently in this case:
https://dl.dropboxusercontent.com/u/19002945/SolvigMM%20Video%20Splitter%20Join%20Manager.png
As you can see, there is no difference between the two .MP4s except for the resolution.

Perhaps the rez of the second clip could be lowered to match that of the first...?  How do I change the resolution of a video?

Oh, that would be great!  Thanks in advance! hehehehehe

Hello WinstonSmith6079,

Unfortunately using our software it is not currently possible to join such files with different parameters of video/audio data.
We also have not got such feature yet to partially remove the video from the selected fragment from the file leaving its audio content. At the present time it can only completely remove video from the file with saving its audio content.
If such features appear in the Video Splitter in future, I'll post at this thread.

Okay, so how can I do what I'm describing, from an .MKV source?

Hello WinstonSmith6079,

Thank you for your post.
Unfortunately Video Splitter's Join Manager at the present time can not join files of different formats or it they have different parapeters of audio, video, bitrate, width, height.
If we will add such feature to Video Splitter's next releases, we will post here.

I want to join two consecutive clips, the second clip containing only its original audio, cutting the original video-track out, see?

Here's the first of the two clips, with original source audio & video, no problem:
https://dl.dropboxusercontent.com/u/19002945/In%20the%20Mouth%20of%20Madness%20%5B1994%5D%20%5BBlu%20Ray%3B%201080p%5D_Trim1a.mkv

The next of the two clips
https://dl.dropboxusercontent.com/u/19002945/In%20the%20Mouth%20of%20Madness%20%5B1994%5D%20%5BBlu%20Ray%3B%201080p%5D_Trim1b1.mkv
like the previous one, contains its original audio & video tracks.

I eventually worked out how to remove the video-track, leaving the audio only, like so:
https://dl.dropboxusercontent.com/u/19002945/In%20the%20Mouth%20of%20Madness%20%5B1994%5D%20%5BBlu%20Ray%3B%201080p%5D_Trim1b2.mkv
So far, so good, I thought.  But when I tried to Join them using the Splitter's Join Manager, it said that they couldn't be joined because of the second having no video-track.

I thought maybe if I could somehow add a blank video-track to the second clip, it would make the Join Manager work, but I don't know how to do that either. 

Please help!