1) Just last night I recorded the full (Uncompressed) movie. It has about 30mins.
First I tried MPlayer Classic to do this, but it stutters after a few minutes. Not good.
Not that suprising, uncompressed video has a stupidly high bitrate. If you want a somewhat more sane source file, capture to either a fast lossless codec like Huffyuv or a *fast* lossy codec like one of the MJPEG variants - those two are designed to be very fast at compression, unlike most other codecs.
Then I tried VirtualDub, but after a few minutes, it messes up the sound (it starts to sound weird)
Now this is suprising. What codec, if any, did you use for the audio, and how does it sound weird?
...The problem is: when the file reached ~4GB, it started another file. So now, for an uncompressed 30 mins movie, I have one file of 3.9GB and one of 2.73GB.
This is a limitation of FAT32 and/or old capture programs. If your drive is NTFS and you're using an intelligent capture program, then the upper limit on file size is on the order of terabytes.
The other limitation is that the original version of AVI can't go beyond 2GB. Fortuantly, most programs use a more recent version of the spec (known as OpenDML) that can create much larger files.
I tried to merge them with VirtualDub, but it says they have different sampling rates (the first has 25.00456 samples/sec, and the second 25.00106). Doh...
This sounds like a mixture of timing issues between the files, and a slight desynchronisation when capturing (not unexpected when the audio and video inputs are on separate devices). I'd just bash both to 25fps, as the error is something like 0.02% (to put that in everyday values, less than a second out in the hour). Note that you may find the resulting audio/video desynchronisation is a problem, in which case I'd do what Dotpitch suggested.
Can anyone suggest a program that I can use to make a movie that takes more then 4GB??
Virtualdub, as long as your hard disk is formatted as NTFS. If not, then nothing can create files greater than 4GB (it's a limitation of FAT32), but Virtualdub can also create multipart AVI files, and is a bit more intelligent than most about it.
2) I already tried 2-pass encoding with Xdiv and also with MS Windows Media 9. But when I try to view the finished movie, BSPlay gives me an error ("The file is corrupted. Seeking will be very slow"). After clicking OK, there isn't any image in that movie...just sound. Did I do something wrong?
As Dotpitch said, 2-pass encoding requries two passes. First time through, in the encoder options select "2-pass: first pass" or similar and give it somewhere to save a temporary file. For the second pass, select "2-pass: second pass", "2-pass: final pass" or similar and give it the temporary file it created in the first pass (this is not the same as the output AVI file).
During the first pass, all the encoder does is note information about the complexity of each frame. In the second pass this information is then used to make better decisions about how to allocate bits.
Something that's not been mentioned here is audio. Unfortuantly you can't easily include Ogg Vorbis in an AVI file, but there's a handful of codecs that can be used. I'd suggest using either uncompressed audio (since it'll often be smaller than the compressed video), Microsoft ADPCM (it's fast, and reasonably good quality) or MP3 depending on your preference. Don't use MP3 when doing the initial capture for the same reason as not using XviD - it's not designed to be a realtime codec. ADPCM is usually fast enough to be useed when capturing. 'course, this depends on how beefy your computer is.