I listened to the first one in which the lecturer asserts that Mohammed is mentioned in the Hebrew Bible Solomon 5:16.
I did some research and this is what I came up with.
Song of Songs 5:16
"His mouth is most sweet: yea, he is altogether lovely. This is my beloved, and this is my friend, O daughters of Jerusalem."
Problem:
The underlined word is the Hebrew Machmaddim. Moslems claim that this word is a reference to Muhammad for two reasons,
1. The word Machmad (singular of Machmaddim) sounds a bit like the name Muhammad
2. The word Machmad means The praised one (i.e. the one worthy of praise); this, they assert, must be Muhammad!
Solution:
1. The logic of the assertion that the word Machmad is Muhammad because the two words sound a bit similar is somewhat specious. The name John sounds a bit like the Arabic Jinn, but there is no connection between the two. Similarly a connection on the grounds that the word means "the praised one" falls short of a guaranteed logical link; has only one person in the world ever been praised?
2. The context of the passage identifies the person described as Machmad as someone in the time of Solomon (Song 3:11) who is loved by a Shulamite (Song 6:13). He is red-haired (Song 5:10). None of these descriptions fits Muhammad who never visited Shunem in his life.
3. A search of all the occurrences of the word Machmad in the Bible shows that the word has nothing to do with praise. It simply refers to whatever is desirable for whatever reason and is derived from the root chamad which means desire.
4. If one is to accept that the word Machmad refers to Muhammad then one should look at all the occurrences of that word. When one does this one can see why only the occurrence in the Song of Solomon is cited by Moslems. The others tell one that Machmad was destroyed (2 Chron. 36:19), was to be laid waste (Isa. 64:10-11), has been taken captive by an enemy (Lam. 1:10), has been traded for food (Lam. 1:11), has been slain by God (Lam. 2:4; Hos. 9:16), has been removed by God (Ezek. 24:16), is to be profaned by God (Ezek. 24:21), is to be buried in nettles (Hos. 9:6) and been carried away by pagans into their temples (Joel 3:5). Even an unkind person would not attribute all these things to Muhammad.
http://www.wrestedscriptures.com/a08islam/song5v16.html
I didn't listen to all 11 but this explanation made a lot more sense to me than the lecturer.