Architect v1.4 introduced an Alternating Feature option that swaps the featured image (or video) left/right with each successive post.
Using Alternating features
To activate the alternating features, in the Content Layout tab, simply:
1) Set the Feature Location to Outside components
2) Enable Alternate features position
3) Set Components area position to either Left or Right
4) And do remember to set the Components area width to less than 100% or you won't see the feature