I signed up for a few Udacity courses a few years ago and never did them... I still have access to everything. Here from the FAQ:
I've been accessing free courseware on Udacity for months (or years!). Do I still have free access now that the course has a paid enrollment option?
You can continue to access all the same free course material just as you had previously. You now also have the option to enroll in the course and continue from where you left off with all the added benefits. We encourage you to enroll in the course and try it risk free for 14 days. We think you're going to love the experience!
How long is a Udacity course available?
Udacity classes usually remain available once they have launched. Once online, our courses are maintained to keep the content up to date and optimized for your learning.
Are there deadlines within each course?
There are no deadlines for Udacity courses. You may complete them at your own pace. However, we do provide guidance as to how long you can expect the course to take if you dedicate ~5 hours per week to the course. With a full course enrollment, your personal Udacity Coach can also help you personalize a schedule and set deadlines to achieve your learning goals.
As for the confusion I had earlier about free vs pay, this answers that:
What's the difference between enrolling in a course vs. viewing free courseware?
The difference between enrolling in a course versus viewing free courseware is like the difference between attending a great class versus simply reading a textbook.
The free courseware contains information, lectures, and auto-graded exercises. By enrolling in the class, you'll get project-planning advice and feedback on what you build to improve your portfolio. You'll also have a personal Coach throughout the course who will review your code, provide guidance on your project, answer questions about the class, and help keep you on track when you need it. After your final project review, you'll also go through an exit interview that Udacity will use to issue a verified certificate of accomplishment that is recognized by leading tech employers.
It sounds to me like your particular course was modified or swapped out, but the norm is for courses and their content to stay in place.
I have not started watching into them yet, but for an exhaustive, all-included video tutorial series, you would be hard-pressed to find something with more content than this one. It can also be more beneficial to have one long tutorial from one source than many smaller ones you patch together to get the bigger picture since it prevents you from continuously rehashing the same material, or missing important things. 
