how can i convert video clips or BS. player files to mp4 or 3gp format?and how can i reduce the length of..?

Pavtube DVD Ripper for Mac boasts fast ripping speed. It is capable of converting DVD to MP4, AVI, MOV, M4V, 3GP, 3G2, MPG, MPEG, FLV， SWF, MKV etc. And it can also convert DVD audio to MP3, M4A, AAC, AC3, WAV, OGG etc.You can try Cucusoft DVD and Video converters suite which includes Cucusoft Ultimate DVD and Video Converter Suite.
It is the best all-in-one DVD and video conversion software converts DVDs and videos to play on almost any portable device including iPod, iPhone, Zune, PSP, video capable MP3 players, video capable mobile phones, and Pocket P.C., etc.

Pavtube iPod video converter can convert all videos like AVI, MPEG, WMV, MKV, RM to iPod video with ease

I know one named FLV to AVI MPEG WMV 3GP MP4 iPod Converter that can convert the flv video to many other video formats and audio format.
I recommend you a useful and free tool that can convert video, rip dvd, Backup DVD and download YouTube video.
Next Video Converter is a free video converter and DVD ripper with easy-to-use graphical interface, fast converting speed, and excellent video quality.

A powerful iPhone Software that can help you convertalmost all the video to iPhone (MPEG4)video format, which could be played on the Windows Media Player.

It can convert almost all video formats including DivX, XviD, MOV, RM, RMVB, MPEG, VOB, DVD, WMV, and AVI to MPEG-4 movie format for iPod, iPhone, PSP or other portable video device, MP4 player, or Smartphones. It can also rip DVD to any video format.
when you say “movie maker” do you mean windows movie maker? windows movie maker is free and therefore very limited, only to wmv and mp3/wma files. so if you’re talking about windows movie maker that’s out of the question. you can find a list of video editing software here
hi, i think Windows Movie Maker is really nice and it accepts wmv file i think.

Software for 3gp 3g2 video converting, convert any video to 3gp 3g2.

so i recommend you Aiseesoft Total Video Converter.
it can convert flv, 3gp, mp4 to wmv file easily.
it can also convert other video formats, such as MP4/MKV/WMV/AVI and other popular formats such as: H.264/MPEG-4 AVC, FLV, MPEG-1, MPEG-2, 3GP, 3GPP, VOB, DivX, Mov, M4V, DivX, XviD, ASF, SWF, VOB, DV, Super VCD(NTSC, PAL, SECAM), VCD(NTSC, PAL, SECAM) , DVD(NTSC, PAL, SECAM) and HD video etc with high speed and excellent sound/image quality
free download it here
here is how to use it:
Step 1: Click the “Add File” button to load your video
Step 2: Select the output profile
Step 3: Output Video settions.
You can cut a clip of your video by using its “Trim” function
You can merge a few videos into one file by clicking “merge into one file”
You can crop the black edge of your video to adjust your video to your iPod screen to get the best view.
Step 4: Click the “Convert” button to sart the conversion.
Just have a try and i hope it can help you.