See this example properly formatted in the QUT Cite tool.
Standard in-text citation examples are in Getting started - In-text citation.
Lecturer, A. A. (Year, Month DD). Unit code Unit title: topic [Format]. Blackboard. https://blackboard.qut.edu.au/webapps/portal/execute/tabs/tabAction?tab_tab_group_id=_3_1
Murray, M. H. (2017, August 27). LLB244 Criminal Sentencing: Module 3 Roles and ethics; The Plea in Mitigation [Lecture recording]. Blackboard. https://blackboard.qut.edu.au/webapps/portal/execute/tabs/tabAction?tab_tab_group_id=_3_1
The APA Blog has Examples on how to timestamp your Lecture recording.
Indicate the format in square brackets after the title, e.g. [Presentation], [PowerPoint slides], [Supplemental material].
Use the login page URL for Blackboard, such as the one here.