1. I captured from a video window in Windows Media Player (QuickTime Player, RealOne Player), but the window shows nothing but black. How can I solve this problem?
By default, all video players (and 3D games) use video acceleration. In video acceleration mode, the graphics are drawn directly to the hardware without going through the Windows layer. In this case, screen capturing applications cannot get the video image. This applies to all screen capture applications, not just Boilsoft Screen Recorder.
To record the image of a video player even a game, open Windows Control Panel, open the "Display" control panel--"Settings" tab --"Advanced...", and then you will see property pages of the graphics card. Select "Troubleshoot" tab, and move the "Hardware Acceleration" slider to "None".
You will notice a sharp retard of the video playback. However, you will be able to capture the screen with the video images, whether by using "PrtSc" button, or using Boilsoft Screen Recorder.
Remember to move "Hardware Acceleration" slider back to "Full" once you complete your screen capture.
2. How can I record audio from the speakers?
You can record all of audio information the PC sends to the speakers as long as the "Port" setting is correct. Different sound card displays different text for the speakers. You should look for "Stereo Mix", "Mono Mix", "WAV", or something similar.
Incidentally, some sound cards do not support capturing from output buffers. If so, please use a suitable card.