The images are easy. Under Settings > Images > General > Include, check both Scaled images and Originals. You can also do this on an image-by-image basis by right-clicking a thumbnail in the Explore view and choosing Include original.

Many skins will automatically do what you want - show the scaled image, but provide a download link to the original. In others, you might need to choose a skin setting to provide a download link - use the search box to find the setting for "download."

But videos? No way. This all goes back to a dopey decision made when video support was added to jAlbum. As a shortcut, David decided to treat processed videos as if they were originals. I screamed bloody murder about it at the time, but I was ignored. The result is that, to this day, you can't include both the original video and the processed video in the same album.

Just perusing the forum, saw this oldish thread and thought of a way to offer a download of the original videos. It might not be elegant but it works.

First zip up each of the original videos. In jAlbum's explore view, where each video is add a folder called, say, 'Orignal_videos' and then mark it as hidden. Now add the zipped video files that match the ones in the the explore view to that folder. For each video add the comment

<a href="../Original_videos/videoName.ext.zip">Download original</a>

Being a zip file jAlbum won't process it and being in a hidden folder the website visitor won't see it. If they click on the 'Download original' link they will be able to download the original video and unzip it.

Example:
Root folder has a video called 'My_video.mp4'
So add to the root folder a new folder called 'Original_videos'.
Using the contextual menu mark the 'Original_videos' folder as 'Hidden'.
Next zip up the original video and then drop it onto the above folder to add it.
Add the comment to the video in the root folder

<a href="../Original_videos/My_video.mp4.zip">Download original</a>

Build the album and try it, It will depend on on the skin used if the comment is added to the thumbnail or slide page.