A couple of things worth trying here.

Firstly breaking the 15 minute clip into useable chunks to place on the time line. The best way to do this is in the Video Editor is to,

1. Place the 15 minute clips in the Production Library. To do this,

a. Make sure the production library is in view (View menu > Toolbars & Panels ... > Check 'Production Library')

b. Click the Production Library window and select 'Media Library'

c. Optional, but I find it a good idea to create a new folder. To do this Right Click the 'Media Library' folder and select 'Create'. Name your folder appropriately.

d. Now click the 'Import Video File' button to locate your 15 minute clips. Your clips (or more correctly 'shortcuts' to them are now in the Production Library.

2. To break the 15 minute clips down into useable clips that you can use again and again do the following,

a. In the Production Library, double click your desired clip. This will now open in the 'Source Window'

b. In the 'Source Window' drag the start and end trim bars to mark your scene as required. (Or press play and simply press F3 to set the mark in point and F4 to set the mark out point ... or use the Jog Dial for precision)

c. Anyway once you have your desired scene simply click and drag from the 'Source Window' to the 'Production Library'

d. Repeat steps a and b as often as you like.

e. To post the clips to the timeline all you have to do is click and drag the appropriate clip from the Production Library to the timeline.

Having said all that, the next time you capture, you may wish trying to use the Capture Tool 'Smart Capture' option, which effectively does all the scene detection for you. Let me know if you nee a guide on this.

As for the preview window playing for only 10 seconds, it is worth checking the following,

1. I recall that the default capture time for video is 10 seconds. You haven't accidentally forgotten to change this by any chance? If you have then the clip will only be 10 seconds long and show as such on the timeline.

2. Have you accidentally set a mark in and mark out time of 10 seconds on the video clip?

3. Have you accidentally played a preview range (of 10 seconds) instead of the full video clip?

Post back and let me know. The good news is that I am not aware of any substantive bugs in Media Studio Pro (been using it for years), so we will get to the bottom of this.

Meantime I hope this helps.