|At least Firewire capture was removed in porting to KDE 5 due to lack of manpower.|
Kdenlive provides functionality for capturing video from external devices; e.g., Firewire, FFmpeg, Screen Grab and Blackmagic.
You configure video capturing from here).(more on this
You define the destination location for your captures by using here).(more on this
To execute a video capture, select the Record Monitor and choose the capture device from the dropdown in the bottom right.
This captures video from sources connected via a firewire (also known as - IEEE 1394 High Speed Serial Bus) card and cable. This functionality uses the dvgrab program and the settings for this can be customized by clicking the spanner icon or choosing . See Configure Firewire Capture.
To perform a capture:
Note: If your device does not start playing the source device when you click the record button, you may have to start playback on your device manually and then click record.
I believe this captures video from an installed Web Cam using Video4Linux2.
This captures video of the PC screen. In version 0.9.2 it uses recordMyDesktop to do the capture. There is an open defect with this functionality in ver 0.9.2 — See bug tracker ID 2643.
In version 0.9.3, the screen grab is done by the ffmpeg functionality instead. For screen capture to work in ver 0.9.3, the version of ffmpeg installed needs to have been compiled with the
--enable-x11grab option. Ubuntu comes with an ffmpeg version compiled with this option.
To check on your linux distro, type
ffmpeg -version in a terminal and look for
--enable-x11grab in the reported configuration info. 
If you are capturing the screen and using the X246 with audio settings and you get a crash as shown in the screen shot ...
... then consider creating a profile for audio capture where
-acodec pcm_s16le is replaced by
-acodec libvorbis -b 320k. See Configure Kdenlive.
ffmpeg -version. The Libav version does not. So this method to check for the
--enable-x11grabdoes not work if you have the Libav version of ffmpeg.