I support this idea, it seems pretty neat. My ideas on how it should be implemented:
-Have the whole thing in an expandable thing, similar to a spoiler tag.
-Have three tabs at the top to alternate between three different types of listing, one that lists by map title and another one that lists by person, and one last one to sort by date.
-The list sorted by map title would be sorted by number of replays watched on that specific map. Each item in the list would be expandable to show the people that have watched that map, with the users ordered by ranking perhaps (so you see which "good" people have watched your replays)
-The list sorted by person would be sorted by ranking, with each item in the list expanded to show the maps they watched, with the maps ordered by date in which they were viewed
-The list sorted by date will literally have every single replay listed in order of date/time with the replays watched since last visiting the profile be in bold.
Examples
(sorting by map)
Sort by:[b] Map[/b] | User | Date
Map #1 [200 replays watched] [+]
Map #2 [150 replays watched] [+]
Map #3 [75 replays watched] [-]
User 1 [rank #5][+]
User 2 [rank #358][+]
User 3 [rank #2342][-]
//additional details here (like date or something, idk)
Person 4 [rank #23423409284] [+]
Map #4 [5 replays watched] [+]
(sorting by user)
Sort by: Map | [b]User[/b] | Date
User #1 [rank #6] [+]
User #2 [rank #75] [+]
User#3 [rank #1232] [-]
Map 1 [+]
Map 2 [+]
Map 3 [-]
//additional details here (like date or something, idk)
Person 4 [+]
User #4 [rank #9001] [+]
(sorting by date:)
Sort by: Map | User | [b]Date[/b]
(bold denotes new replayed watched by others since last visiting your profile)
[b]Map #1 viewed by User #1 on Date #1
Map #2 viewed by User #2 on Date #2[/b]
Map #3 viewed by User #3 on Date #3