Why does Javascript Jabber mp3s seek perfectly on Chrome, but most do not?

[mitchdowney]

This is interesting. Javascript Jabber and Art of Charm mp3s appear to seek perfectly on Chrome. What is different about their mp3s that allows Chrome to seek in them, while most of other mp3s only seek very inefficiently?

Javascript Jabber example:
https://podverse.tv/episodes/4978/

Javascript Jabber mp3:
http://traffic.libsyn.com/jsjabber/JSJ118DeveloperSkills.mp3

Art of Charm example:
https://podverse.tv/episodes/2593/

Art of Charm mp3:
http://traffic.libsyn.com/theartofcharmpodcast/281VanessaVanEdwards.mp3

Sample mp3 links that do not seek perfectly on Chrome (they download whole episode until seeking to unbuffered position):

Joe Rogan Experience mp3:
http://traffic.libsyn.com/joeroganexp/p525.mp3

Adam Carolla mp3: http://www.podtrac.com/pts/redirect.mp3/traffic.libsyn.com/theadamcarollashow/2014-07-25acs_2014-07-24-213718-7770-0-1-0.64k.mp3

Monday Morning Podcast mp3:
http://traffic.libsyn.com/billburr/MMPC_7-21-14.mp3

Dan Carlin mp3:
http://feedproxy.google.com/~r/dancarlin/history/~5/bB9DB06Bksg/dchha52_Blueprint_for_Armageddon_III.mp3