Great tutorial houkouonchi! I also heard that this may have issues (as you also point out in your video) that with latency being different on the WAN links causing reordering and reducing performance. Did you ever try to bond a T1 and a 6Mbps DSL line? I wonder if that will work or will the latency difference just kill it?
I heard good things about the Broadband Bonding routers by a company named Mushroom Networks (funny name 😆 ), which I believe also are based on Linux that accomplishes VPN bonding over varying latency WAN links. Rather than using round robin, it dynamically adjust the scheduling algorithm to get around the latency issues. I am thinking going that route as we don’t get Fios here and T1 and DSLs are our only options.