It's easy! To record Skype calls with Screenflick, you simply need to change the "Speakers" setting in Skype's Audio/Video preferences to "Same as System" or "Soundflower (2ch)" so the audio is recorded.
By default Discord will get recorded right out of the box, but if you've changed your Discord audio settings, you may need to simply change them again. It'll take 2 seconds.
This is just a precaution that macOS does for all system extensions. It only takes one click of a button to enable it.
This is OS X's DRM (Digital Rights Management) protection at work. If you're recording a clip from a DVD using the Apple DVD Player application, you can use an application called "VLC" as a work around.
When you start a recording with system audio turned on, Screenflick switches the system-wide default audio output device to the "Soundflower" virtual audio device, which Screenflick then uses as an input to record audio from. Some programs unfortunately will play all audio over a specific output device determined when the application launched rather than always using the current system setting which can lead to problems like this.
What needs to happen is the program playing audio needs to decide that it should play that audio to the Soundflower device, rather than your speakers. There are two ways this can happen.
The file size of the resulting movies is completely dependent on the video compression settings you choose for the export. Screenflick assumes you have some knowledge of them because there are a lot of choices and trade offs for various applications, and there is no one-size-fits-all solution. However, for a one-size-fits-most guideline, you can stick to using QuickTime exporter, selecting H.264 video compression, 96kbps AAC for audio compression, and use the "Quality" slider to determine the movie quality and thus, movie size.
It's darker because the game alters the physical display's gamma curves. You just need to change the brightness in Screenflick before exporting.
There are three key factors to improving recording performance in Screenflick.
When recording video games or other programs with high performance OpenGL graphics, make sure the game has V-Sync turned on. With V-Sync off, the frame rate of the game can go above the maximum of the display (and the chosen recording FPS in Screenflick) which can steal precious GPU processing power away from Screenflick.
Some fullscreen games will change the screen resolution when they start. If the recording started before the game launched, this can cause the recording to stop. To handle this, use the "Record Fullscreen After…" feature and select when "Screen Resolution Changes". Also, read about some performance tips.
The movie preview in the export view of Screenflick is a rough preview, and can play back at a lower frame rate than the actual recording. For a true representation of the speed/smoothness of the recording, export it and watch it in QuickTime player.