The best way is to capture the game in normal speed and be able to get the raw unaltered and still interlaced (this is important) 29.97 frames per second capture onto your computer. Most 'user friendly' capture programs try to deinterlace this source capture for you since interlaced video does not display well on a progressive display like your computer, and you need to avoid this being done.
When done properly, this method will always be 100% correct, so it's the next best thing to a debug mode for finding frame data. It's also pretty quick once you know the process. I did very thorough and detailed frame data for Luigi for Brawl in like 4-6 hours including all IASAs, hitbox windows, autocancels, hitlag/stun/advantages disadvantages (lol Brawl), etc.
http://www.smashboards.com/showthread.php?t=175652
An important thing to mention is that the invincibility 'flashing' isn't actually a true representation of when you're invincible like in Melee. I noticed this when I did Luigi's stuff. The only way to find it is to test it directly to see the frames where they begin not getting hit for the start of the window and begin getting hit again for the end. I never bothered to redo this for Luigi since I've played the game maybe twice or something since then back in June, lol.
In NTSC the game runs at 59.94 frames/game images per sec, and when you capture through composite (the basic yellow video cable) or S-Video the signal that is carried is 29.97 interlaced frames per sec, which is actually 59.94 fields per sec with each field representing 1 game 'frame' and there are 2 of these fields in each interlaced frame.
So in reality every game frame you need is actually there in a basic normal speed capture, but 99% of the time when programs deinterlace the video they scrap 1 of those fields for viewing on a computer and you are left with a 29.97 progressive video (1 image per frame) and so half of the game frames are lost.
To get around this you need to do the deinterlacing yourself, and instead of scrapping half the fields you want to separate the fields into separate frames creating a 59.94 frames per sec progressive video. You could also capture through component to get 59.94 progressive, but I believe capture cards that have these particular inputs are extremely expensive/aren't readily available for consumers. With this all you need is any basic capture card/gamebridge/whatever.
I use VirtualDub (to do the capture and to view it) along with AviSynth which can do the proper deinterlacing method for this purpose. I begin to go over how I do it here and in my next 2-3 posts or so in that thread:
http://smashboards.com/showthread.php?t=163775&p=4338287
I also explain some things about the video signal that is captured, interlaced video, deinterlacing, and how it applies when wanting to get all 59.94 (aka 60) game images/frames per second from the captured video signal here:
http://smashboards.com/showthread.php?t=162023&p=4308928
Also, like I mentioned in that first thread explaining it, you should be sure to record the move being done at least twice just in case a field happens to be added/dropped at the same time you used the move which could cause the data to be off by 1 'frame' on occasion. Having that to double check, and also having the in-game timer on will make sure the numbers you get are exact.
If you happen to have an S-Video connection for input and a cable that has an S-Video out from the game you should use that. The signal is basically the same as the normal composite (yellow), just that the image you get is a bit clearer which helps with reading things like Brawl's tiny game clock numbers.
When capturing, I recommend using a lossless codec or at least a very very high bitrate with a codec like XviD/Divx or something if you don't have adequate hard drive space for a lossless capture. The reason being that you don't want to get compression artifacts across the interlaced fields, which would distort fine details in the image that after you deinterlace it will make things like the game clock difficult or impossible to read.
I myself use the Lagarith Lossless video codec if you want a suggestion for one:
http://lags.leetcode.net/codec.html
