In some cases, you can copy, paste and print; however the allowable amount varies by publisher. Most of the e-books in EBSCO and eBook Central have a copy, paste and print allowance.
EBSCO:
If you are printing an eBook, up to 100 pages of a title can be printed per user in PDF format. In addition, you can select to save the pages as a PDF file instead of printing them. Availability of copy/paste functionality is determined by the publisher, and that information is presented in the Publisher Permissions information on the detailed record and in the eBook viewer.
eBook Central:
The default allowances are 40% for print and 20% for copy. Publishers may choose to modify these defaults on eBook Central, but typically they do not. eBook Central displays the patron's remaining copy and print allowances for each title when they are signed in.
BibliU:
In BibliU, you can copy text from your eBooks quite easily - simply highlight the text you wish to copy and this will automatically bring up the annotation menu. On the annotation menu window, click the Copy icon and then paste the copied text to your document.
If you see the message, "copying is disabled for this book" then this is referring to the copying allowance set by the publishers of the book. Some publishers allow more allowance than others, while there are also some publishers who don't even allow their books to be copied at all (0% copying allowance).
Part of BibliU's agreement with the publishers to distribute their content includes copyright protection, so unfortunately if this message comes up then that eBook is not available to copy.