on a Mac? YAY!!!! Good for you.
Quicktime Pro is probably all you need to generate good enough sample clips of your videos. Don't see a point in using Flash for this: it will be more trouble for you than it will be worth. Seems many people think Flash is the superhero for solving all the problems that pertain to anything that moves or makes a sound. It definitely has strong points, I use it extensively and know it well, but for simple video delivery in a web page, it is absurd to even consider Flash.
Using the settings suggested above should help get your file sizes down. When dealing with multimedia on the web, compromise is the rule. You can't expect your video to play like TV without streaming, but you can still achieve decent quality from an http server, provided you follow some guidelines.
Reduce the size of the video. Standard web playback of video is rarely over 320 pixels wide, and the reason for this is to reduce the file size while still maintaining quality.
Sound is important. Unless the soundtrack absolutely MUST be in stereo, reduce it to mono. This setting will sum the left and right channels into one single channel that will playback through both speakers. By doing this, you can cut the file size of the sound by 1/2.
If it is still too big, reduce the sampling rate, but be careful. CD audio is recorded at 44kHz for a reason. Reducing the sampling rate will cause high frequencies to sound 'mushy' or squashed. If the soundtrack is complex, reducing the sampling rate too much may make it sound unclear. However, if the sound is only speech, there is a setting in QT Pro that reduces the sound band to only include the frequencies present in normal speaking.
Quicktime is you best bet for delivery from an http server, due to the 'progressive download' ability. What this means is that the video file will buffer enough of the clip to begin playback (without having to wait for the whole file to download).
You can also consider the Helix Producer from Real Networks....it is another free encoder that sometimes produces better results than QuickTime. There is currently no OS X version, but you can download the OS 9 version. If you are running OS X, it will operate fine in classic mode.
Embed the video in the webpage using the <object> and <embed> tags as in the sample code below. If you must, create a seperate window to 'pop out' of the web page that holds the video. You can do that by using JavaScript.
I did that on a site I recently created:
http://www.liquidassetsnj.com/ghost.html
Check out the sourcecode of the .../ghost.html page to see the Javascript function I wrote to pop the window out. Check the sourcecode of the movie player window to see how the files are embedded.
Here is some sample code for using <object> and <embed> with Quicktime:
<object classid="clsid:02BF25D5-8C17-4B23-BC80-D3488ABDDC6B" width="320" height="240" codebase="http://www.apple.com/qtactivex/qtplugin.cab>
<param name="src" value="PATH TO YOUR .mov FILE HERE">
<embed src="PATH TO YOUR .mov FILE HERE" width="320" height="240" pluginspage="http://www.apple.com/quicktime/download/"></embed>
</object>
If you plan on doing more of this in the future, consider paying a web host for a streaming server. Also check out the "Streaming Media Bible" by Steve Mack. I use this book in the class I teach at NYU, Sound Design for the Web. You can also consult the page I set up for the class for more information, links, and help.
http://homepages.nyu.edu/~rjc223/SoundDesign
If it is too much trouble for you to learn all of this, try using a professional service. Consider, my company, .:amorphicmedia:., for example.
hope this helps.