**System Information**
Windows 7, 32 bits; Radeon graphics card (but this is not a graphic card error)
*I can test on a Debian Stable 64 bits with nVidia if needed
**Blender Version**
Broken: 2.76 48f7dd6
Worked: all previous stable releases since... 2.68 maybe?
**Short description of error**
Strips are overlapping (being placed over each other) when using means that are not Grabbing (G).
**Exact steps for others to reproduce the error**
You shouldn't need a .blend file from me to reproduce this error. Exact steps are:
1. Add a movie to scene; it is important that you add a video with audio. Now you have:
1 audio (channel 2)
1 video (channel 1)
2. Shift+D and duplicate the video; place it exactly above the original video. Now you have:
1 audio (channel 4)
1 video (channel 3)
1 audio (channel 2)
1 video (channel 1)
3. Select your audio strip (channel 4) and, on the strip data panel, change its channel to -1 (say, from 4 to 3). The strip immediately goes to channel 1, overlapping the video strip is there. The same happens if you do these steps with the video from channel 3.
4. Now this is interesting. Undo the changes and go back to step 2. Select the audio strip (channel 2) and change its channel to 1. The audio strip recognizes that a video strip is there and is placed after it, instead of over it.
5. The same happens if you do these steps with python.
6. Curiously, this does not happen if you Grab (G) the audio+video strips and place them overlapping the other - they will recognize the former and be placed before or after it. This was the default behaviour in Blender in all previous releases.