I rarely get a chance to go to technical conferences, but I do watch lot of videos. I tweet about the good ones; here's a collection for posterity:

• Julian Storer at JUCE 2015 talking about rewriting zlib in C++. Some of his points felt very relevant to my day to day coding - reduce access levels (i.e. make stuff private), after adding a bunch of local variables over time revisit the thing and see if there are new abstractions, rename variables rather than commenting.
• Jason Clark at RubyConf 2015 talking about Ruby and GDB. The concepts James talks about are more or less the same in lldb, just a few small syntax tweaks.
• James Adam at RubyConf 2015 talking about refinements.
• Eric Evans at QCon 2009 on Strategic Design. Lots of great insights on core domain and such-like.
• Peter Harkins at RailsConf 2015 on What Comes After MVC.
• Andrew Clay Shafer's 2014 Velocity conference talk on organizational learning. If you're short on time, just watch the 2-3 minutes on dimensions of the learning organization.
• Starr Horne's discussion of TCP and HTTP.
• A game each day for 7 months from Chris DeLeon.
• Aaron Quint's discussion of Ruby 2.x performance tools.
• Cameron Dutro's talk on doing more with AREL.
• Dave Thomas' keynote at ElixerConf 2014.
• Koichi Sasada's talk on Ruby core and whatnot at RedDotRuby 2014.
• Really enjoyed this one - Andrew Turley's talk at GoRuCo 2014 entitled What We Can Learn from COBOL.
• Michael May's talk at GoRuCo 2014 on edge caching.
• A good discussion of the JavaScript execution model from Philip Roberts.
• Alexander Dymo's RailsConf 2014 talk on Ruby Performance Improvements.
• Sam Livingston-Grey's talk at RailsConf 2014 on Cognitive Models.
• A lively talk from Toby Hede on data stores.