external downloaders with youtube dl gui

[ExtendedDev]

Is it possible to properly configure an external downloader, such as aria2c with y-dl-gui? The same cl argument --external-downloader aria2c is functioning normally with the cl version. For instance, using the following arg in gui version: aria2c --external-downloader "download" is "completed" with status finished in main window. In this case, nothing is downloading. The same thing happens with following args:
--external-downloader aria2c
youtube-dl --external-downloader aria2c
youtube-dl-gui --external-downloader aria2c

[Korons]

Have you tried adding --external-downloader aria2c to the commands tab in the options window of youtube-dl-gui?

[Korons]

I just tried adding --external-downloader aria2c to the command tab of youtube-dl-gui and it worked fine (aside from throw a WARNING: Requested formats are incompatible for merge and will be merged into mkv.)