Lag? Why? They use a background CPU to do these tasks... not the main CPU, GPU or RAM.

I'm sure they will use some high encoded codec like h264, x264 or xvid... YouTube videos are 700kbps that means ~500MB for 15 minutes of 1080p video.

In that case it will take a loooooooooong time to encode. 

That pretty much covers it.

PS4 also has a custom chip dedicated to video capture. I haven't heard the same of Xbox One. It seems this video recording will take up system resources on Xbone, which is probably the reason for the limited 5 minutes.

Use live stream then,when you end your stream,you will get the recorded video less than 20 seconds

lol, really are we gonne do a pissing contest on that ??? I'm pretty sure if Sony or MS want to allow you to record the entire play through, they can. 1 min, 2min, 10 min, 5 hours is almost the same. and in MS case I'm pretty sure they will if it's not them it will be an app you can get on the store.
But I'm sure on both you'll be eventually able to chose the default length.

Thus the bad quality

Depends on streamer setting

I have a friend set the upload bitrate 7000 kpb/s,but i'm not sure is there any people can handle that while watching his stream lol

Wat? Please provide me a link, this would be massive.

ehh, not liking either. Cool features but ill stick with capture cards for recording gameplay. Editing will be much better on my computer than on PS4/X1.

If im not recording ill just stream to twitch.tv. I see both of these as basically useless with such low times and probably not proper editing tools.  For example montages sometimes takes hours and hours of gameplay to make a proper montage.  Also the popular ones has pretty good editing skills.  No offense to anybody.

No link... just a normal Windows 8 core uses 25GB disk space... you will have three of them with optimizations... so just guesswork but I think it will be close.

BTW the PS4 reserves 42GB of the HDD for system data in the early devkits.