If you think you are just watching too much DotA commentary and are bored/sick/tired of the commentator's accent and what so ever. You can easily make you own DotA commentary and upload onto Youtube or other video sharing websites. It is very easy and you should believe me.
Things You Will NeedYour brain
Video Editing and Compressing Software
Search for good DotA replays
It is very very important to search good DotA replay. If the replay do not have exciting gank fight/team fight/turning points, then do not bother about them any more. Normally what I will do is to look through what competitions are going on currently (ADC, WCG, et), usually the highly competitive competition do have a lot of good replays which are freely distributed.
Analyse the replay
Before doing the actual recording, I think it is necessary to know when is the first blood/team fights/gankings/. It is really bad to miss the first blood. It is not necessary to watch the whole replay but knowing when to switch the screen is important. If you are missing a lot of kills, your viewers will not be so happy about it. A good software to use here is the DotA Replay Manager which pretty much save you the time to watch the whole replay. Just google it, then you can easily find it online.
Recording is the most important part. There are several software (e.g. ViewletCam
Camtasia Studio, Fraps) online allowing to record your screen. The one that I am using is Fraps. It does not matter which software you use, they all have good avi file output. I recommend to set the fps to 15 or 20 with half size. From my personal experience, 15 fps (half size) will output a 4GB file everything 20mins. I suggest you to get at least 20GB just for the recording part because Fraps really output good quality file which is freaking huge. 15 fps (full size) will out a 4GB file every 10mins or less. If you are using this setting, then get at least 50GB free disk space I think.
Before doing the recording, it is necessary to do a research on the both teams especially which player is in which role. During the commentary, there isn't a fix way to comment. There are few tips here. Always comment on the following things, line-ups, creeps kills(carry), item build, skill casting sequence, fog dodging, warding and much more to find out yourself.
It is a painful process for me especially the rendering part which usually takes up to half of hours. There is a lot of video editing software out there as well, some are free and some needs to be purchased. I will just name a few you want to try out. Microsoft Movie Editor, Sony Vegas, Adobe Pr, Adobe After Effect. Some compressing software to test out with, WinAVI Video Converter, Easy RealMedia Tools Sorenson Squeezeï¼ˆVP6, FFmpeg. You can find respective tutorials of different video editing software and manual for compressing software online so I will not be talking on how to use them. One important thing I must say is that try to do a balancing between the quality and file size.
There are tons of free video sharing websites online. Youtube is one of the more popular ones but not the only one. I suggest you to try out different sharing website before fixing into one.
There are few websites you can visit to watch some of the good examples of DotA Commentary videos
Youtube - a tons of good DotA Commentary videos can be found
DotA Commentary - a collection of good DotA Commentary videos