Mityvac Brake Flush/Bleeding

Flushing your brake fluid might be a good idea at 100,000 miles or sooner, depending on how you drive and your driving conditions. Brake fluid is hydroscopic, meaning it absorbs water; mainly humidity in the air. High temperatures, as well, ruin brake fluid.
But if you're not doing any hard braking with your vehicle, and your brake system is closed to the air, your fluid may be perfectly good at 100,000 miles. That's probably why neither Toyota or GM have recommended brake flush intervals in their Pontiac Vibe/Toyota Matrix user's manuals. Brake flushes aren't necessary under normal driving conditions within the warranty period. Nonetheless many mechanics recommend flushes as much as every 30,000 miles as preventative maintenance. You decide.
You do need to bleed the brakes however, after brake work. With your Mityvac you can do both. Bleeding the brakes purges air bubbles from the brake lines, while flushing involves the complete removal of old fluid with new fluid. Personally I have always used the turkey baster method of flushing the brakes; every year or so I suck out the old fluid from the brake master cylinder fluid reservoir. It takes about thirty seconds. Then I top it off. That's why the fluid in this video is so clean despite the fact that this vehicle has never had a full brake fluid flush through the brake lines. In my area DIYers can dispose of their brake fluid at Advance Auto.
Good luck on your project.