My bad, I didn't see the description:
Spoiler :
Title - Artist - Song Length
America - The Ancient Era by Patrick McAvinue and Brad Kolodner 02:53
America - The Medieval Era by Geoff Knorr 03:13
America - The Industrial Era by Geoff Knorr 04:40
America - The Atomic Era by Geoff Knorr and Phill Boucher 03:49
Arabia - The Ancient Era by Kylie Hilali 02:39
Arabia - The Medieval Era by Geoff Knorr 03:27
Arabia - The Industrial Era by Geoff Knorr 04:00
Arabia - The Atomic Era by Geoff Knorr and Phill Boucher 03:51
Aztec - The Ancient Era by Roland Rizzo 01:22
Aztec - The Medieval Era by Roland Rizzo 02:44
Aztec - The Industrial Era by Roland Rizzo 03:34
Aztec - The Atomic Era by Roland Rizzo and Phill Boucher 03:30
Brazil - The Ancient Era by Cesar Garabini and Kahil Nayton 02:44
Brazil - The Medieval Era by Geoff Knorr 04:05
Brazil - The Industrial Era by Geoff Knorr 03:53
Brazil - The Atomic Era by Geoff Knorr and Phill Boucher 03:34
China - The Ancient Era by Bing Xia 01:56
China - The Medieval Era by Geoff Knorr 03:36
China - The Industrial Era by Geoff Knorr 03:35
China - The Atomic Era by Geoff Knorr and Phill Boucher 03:19
Egypt - The Ancient Era by Chakib Hilali 02:12
Egypt - The Medieval Era by Geoff Knorr 03:11
Egypt - The Industrial Era by Geoff Knorr 06:02
Egypt - The Atomic Era by Geoff Knorr and Phill Boucher 05:37
England - The Ancient Era by Geoff Knorr 01:59
England - The Medieval Era by Geoff Knorr 04:09
England - The Industrial Era by Geoff Knorr 03:59
England - The Atomic Era by Geoff Knorr and Phill Boucher 03:42
France - The Ancient Era by Roland Rizzo 03:07
France - The Medieval Era by Roland Rizzo 03:14
France - The Industrial Era by Roland Rizzo 03:32
France - The Atomic Era by Roland Rizzo and Phill Boucher 03:28
Germany - The Ancient Era by Geoff Knorr 01:37
Germany - The Medieval Era by Geoff Knorr 03:47
Germany - The Industrial Era by Geoff Knorr 04:01
Germany - The Atomic Era by Geoff Knorr and Phill Boucher 03:59
Greece - The Ancient Era by Geoff Knorr 01:22
Greece - The Medieval Era by Geoff Knorr 03:13
Greece - The Industrial Era by Geoff Knorr 04:18
Greece - The Atomic Era by Geoff Knorr and Phill Boucher 04:00
India - The Ancient Era by Deepak Ram 02:05
India - The Medieval Era by Geoff Knorr 03:25
India - The Industrial Era by Geoff Knorr 04:52
India - The Atomic Era by Geoff Knorr and Phill Boucher 04:38
Japan - The Ancient Era by Ronnie Nyogetsu Reishin Seldin and Geoff Knorr 02:44
Japan - The Medieval Era by Geoff Knorr 04:05
Japan - The Industrial Era by Geoff Knorr 03:43
Japan - The Atomic Era by Geoff Knorr and Phill Boucher 03:40
Kongo - The Ancient Era by Geoff Knorr 01:57
Kongo - The Medieval Era by Geoff Knorr 03:43
Kongo - The Industrial Era by Geoff Knorr 03:09
Kongo - The Atomic Era by Geoff Knorr and Phill Boucher 03:05
Norway - The Ancient Era by Sissel Morken Gullord 01:21
Norway - The Medieval Era by Roland Rizzo 03:09
Norway - The Industrial Era by Roland Rizzo 03:31
Norway - The Atomic Era by Roland Rizzo and Phill Boucher 03:53
Rome - The Ancient Era by Roland Rizzo 02:01
Rome - The Medieval Era by Roland Rizzo 03:39
Rome - The Industrial Era by Roland Rizzo 05:39
Rome - The Atomic Era by Roland Rizzo and Phill Boucher 04:40
Russia - The Ancient Era by Andrei Saveliev 02:19
Russia - The Medieval Era by Geoff Knorr 03:57
Russia - The Industrial Era by Geoff Knorr 04:34
Russia - The Atomic Era by Geoff Knorr and Phill Boucher 04:18
Scythia - The Ancient Era by Sandro Freidrich 01:30
Scythia - The Medieval Era by Geoff Knorr 03:56
Scythia - The Industrial Era by Geoff Knorr 04:23
Scythia - The Atomic Era by Geoff Knorr and Phill Boucher 04:11
Spain - The Ancient Era by Benjamin Beirs 01:17
Spain - The Medieval Era by Geoff Knorr 03:49
Spain - The Industrial Era by Geoff Knorr 04:33
Spain - The Atomic Era by Geoff Knorr and Phill Boucher 04:13
Sumeria - The Ancient Era by Geoff Knorr 02:34
Sumeria - The Medieval Era by Geoff Knorr 03:27
Sumeria - The Industrial Era by Geoff Knorr 03:17
Sumeria - The Atomic Era by Geoff Knorr and Phill Boucher 03:05
So, it looks like the total duration is 4:21:15.
Not sure about which ones are there in that video, I only recognised the russian one
So about twice Endless Legend, around four times the new MoO. Shorter than Civ IV and V, but no slouch by any standards for an original score.