There are 2 standard transitions - Blur and Gliding which do something similar without the red bar
They are on the Fades tab - here you also get extra options as shown below
If you want a bar as in the clip then you need to add a solid colour image - there are some available under Effects tab, Design elements, Test images - manually set its height to the height of the project and the width as require.
Use keyframes to animate its movement - Effects tab, View/animation, Size / Position dialog ( Effects tab, Movement effects, Size / Position ) in older versions of MEP.
There are 2 standard transitions - Blur and Gliding which do something similar without the red bar
They are on the Fades tab - here you also get extra options as shown below
If you want a bar as in the clip then you need to add a solid colour image - there are some available under Effects tab, Design elements, Test images - manually set its height to the height of the project and the width as require.
Use keyframes to animate its movement - Effects tab, View/animation, Size / Position dialog ( Effects tab, Movement effects, Size / Position ) in older versions of MEP.
The Blur and Gliding transitions are not linear motion they accelerate and decelerate at the start and finish of the transition.
This means when using keyframes to animate a coloured bar you have to adjust the positioning to maintain the bar in the correct position as shown below
in addition changing the transition length after creating the moving bar means you have to readjust the coloured bar keyframes again.
I have found it best to keep all the transitions the same length and adjust the coloured bar length so it is 1 or 2 frames overlap at the start and end of the transition as shwn in the image above.
here is a quick example - pure MEP no addons .
Looks like John CB has also done this a different way.
I finished the one using Xara and then took up the challenge to make the transition just in MEP.
Track 1 - first video
Track 2 - simple white background image, full screen, with keyframes at 0s with X = -1940, at 1s X = 0, gave it chromakey alpha (arrow downwards)
Track 3 - second video
Track 4 - simple red background image, full screen then used Section to reduce width to 1 which gives width = 20 in Size/Position. KF at 0s, X = -20, 1s X = 1920.
Background images either came with MEP2016 or I copied them from a previous version - under Effects, Design elements, Test images.
Here is the result. I find in all cases too much flickering. Maybe slowing the effect down would help.