What's the difference between "Standard" and "High" quality? This is what Roxio has to say about it, but it's not too specific:
From the Video Quality pop-up menu, select the type of video encoding Toast uses to record your disc:
• Standard. This type of encoding takes less time to encode, but the quality is generally not as good as the High option. You might choose this option if faster encoding speed is more important to you than the video quality.
• High. This type of encoding takes more time to encode, and the quality is generally better than the Standard option. You might choose this option if video quality is more important to you than a faster encoding speed.
• Note: Regardless of which Video Quality setting you choose, Toast automatically adjusts the encoding rate to use all available space on a disc. Putting less content on a disc will provide better quality than more content. This has no effect on recording time.
BTW, are there any issues you've come across with Toast 6.1.1 in Tiger 10.4.2? I've tried burning some videos (total is less than 90 minutes) into a DVD with Toast 6.0.9 on the High setting, but it craps out during the encode. Now I'm trying Toast 6.1.1 on the Standard setting.
NB: I tried a test disc before with exactly half the video (on the High setting), and it worked fine, for a disc size of 1.8 GB.