Here is my script to download a video if its video-id is known:
youtube-dl -f 134 -ciw -o video.mp4 https://www.youtube.com/watch?v=xxxxxxxxxxx
Is there any way by which I can download the latest video from now on from a particular channel as soon as the video is uploaded using cronjob or some other method?
As far as I know there is no method that is implemented into youtube-dl directly to download the latest video.
You can use the Youtube Data API to get the Channel's Upload Playlist-ID.
https://developers.google.com/youtube/v3/docs/channels/list
After that you can periodically poll the Videos that are on the Upload Playlist of that Channel.
https://developers.google.com/youtube/v3/docs/playlistItems/list
There is an SDK for Java for example, so you could write a Java Application to retrieve the latest Upload, and then launch the youtube-dl Process like this.
Here is an example to retrieve your own Uploads using the Youtube API (just to get you started).